Hello, friends! In this article we tried to answer numerous of your questions regarding random access memory. ? How can I find out what RAM I have installed and how much? How to choose the right RAM for your computer. How do you know if your RAM is running in dual channel mode or not? What is better to buy, one 8GB DDR3 memory stick or two 4GB sticks each? And finally.
- If you are interested, or, also read our articles.
- Hello admin, one of my friends asks me to install more RAM. The computer properties show a capacity of 2 GB. We turned off the computer, opened the system unit, there was one stick of RAM, took it out, and there were no marks on it. Interestingly, it was not possible to determine the model motherboard. The computer was purchased a long time ago, so the question arose - how to find out the type of RAM it needs? After all, RAM differs in type, frequency and timing.
- Hi all! I wanted to buy additional RAM, I removed the cover of the system unit, took out the RAM stick and I can’t decipher the information written on it, it’s just written there serial number that's all. It is completely unclear at what frequency it operates and what type it is, DDR3 or DDR2. How to distinguish DDR3 from DDR2 memory, how do they differ in appearance?
- I have one stick of 4 GB DDR3-1600 RAM in the system unit, I want to install another stick, also 4 GB, but running at a higher frequency DDR3-1866. Will my computer work normally, and most importantly, in dual-channel mode?
My friend installed three RAM sticks of different sizes and frequencies into the system unit. Is this allowed? But what’s strange is that his computer works fine! - Tell me, how can I check whether my RAM works in dual-channel mode or not? And what conditions are needed for my memory to work in dual-channel mode. Same volume? Same frequency or same timings? How much faster does a computer run in dual-channel mode than in single-channel mode? They say that there is also a three-channel mode.
- What will work better, two sticks of 4 GB of RAM in dual-channel mode or one stick, but with a capacity of 8 GB, respectively, the memory mode will be single-channel?
To find out all the information about a RAM module, you need to carefully examine it; usually the manufacturer labels the RAM with the proper information about the frequency, volume and type of RAM. If there is no such information on the module, then you need to find out everything about the motherboard and the installed processor; sometimes this action turns into a whole investigation.
- Important Notes: Friends, do not forget that all new processors Intel Core i3, Intel Core i5, Intel Core i7 The RAM controller is located in the processor itself (previously it was controlled by the north bridge of the motherboard) and the memory modules are now directly controlled by the processor itself, the same applies to the latest AMD processors.
- This means that it doesn't matter what RAM frequency your motherboard supports. It is important what RAM frequency your processor supports. If your computer has a processorIntel Core i3, Intel Core i5, Intel Core i7, then the officially supported memory standards of these processors: PC3-8500 (DDR3-1066 MHz), PC3-10600 (DDR3-1333 MHz), PC3-12800 (DDR3-1600 MHz), it is at these frequencies that your RAM will operate, even if the motherboard's passport indicates that the motherboard can work with PC3-19200 high-frequency RAM memory sticks (DDR3-2400 MHz).
- It's another matter if your processor has unlocked multiplier, that is, with the letter “K” at the end, for example CPU Intel Core i7-4770 K, 3.5 GHz. An unlocked multiplier means that in a computer with such a processor you can install memory sticks of the highest frequency, for example DDR3-1866 MHz or DDR3-2400 MHz, such a processor can be overclocked and during overclocking the RAM will operate at its frequency of 2400 MHz . If you install the RAM stick DDR3-1866 MHz or DDR3-2400 MHz into a computer with a conventional processor, that is, with locked multiplier without letter" K” at the end, for exampleIntel Core i7-3770, 3.9 GHz then such a bar will work at best at a frequency DDR3-1600 MHz, and in the worst case, the computer will not boot. Therefore, buy RAM that is suitable for your processor.
- Concerning processorsAMD recent years, then they work with memoryPC3-10600 (DDR3-1333 MHz).
Firstly, the RAM stick itself should contain all the information you are interested in, you just need to read it correctly. I don’t argue, there are memory strips that have practically nothing on them, but we can handle them too.
For example, let’s take a Hynix RAM stick, it has the following information: 4 GB PC3 – 12800.
What does the following mean:
firstly, the volume is 4 GB,
secondly, 1Rx8 - Rank - a memory area created by several or all chips of a memory module, 1Rx8 are single-sided memory ranks, and 2Rx8 are double-sided memory ranks.
As you can see, this bar does not say that it is DDR2 or DDR3, but the throughput of PC3-12800 is indicated. PC3 is a designation for peak bandwidth belonging only to the DDR3 type (for DDR2 RAM the designation will be PC2, for example PC2-6400).
This means that our Hynix RAM stick is DDR3 and has PC3-12800 bandwidth. If the bandwidth of 12800 is divided by eight and you get 1600. That is, this DDR3 memory stick operates at a frequency of 1600 MHz.
Read everything about DDR2 and DDR3 RAM on the website
http://ru.wikipedia.org/wiki/DDR3 and everything will become clear to you.
Let's take another RAM module - Crucial 4GB DDR3 1333 (PC3 - 10600). This means the following: volume 4 GB, memory type DDR3, frequency 1333 MHz, PC3-10600 bandwidth is also indicated.
Manufacturer Patriot, capacity 1 GB, PC2 bandwidth – 6400. PC2 is a designation for peak bandwidth belonging only to the DDR2 type (for DDR3 RAM the designation will be PC3, for example PC3-12800). We divide the bandwidth of 6400 by eight and get 800. That is, this DDR2 memory stick operates at a frequency of 800 MHz.
One more plank- Kingston KHX6400D2 LL/1G
Manufacturer Kingston, bandwidth 6400, type DDR2, capacity 1 GB. We divide the bandwidth by 8, we get a frequency of 800 MHz.
But this stick of RAM has more important information, it has a non-standard microcircuit supply voltage: 2.0 V - set manually in the BIOS.
RAM modules differ in the size of the contact pads and the location of the cutouts. Using a cutout, you will not be able to install a RAM module in a slot not intended for it. For example, you cannot install a DDR3 memory stick in a DDR2 slot.
Everything is clearly visible in this diagram.
Sometimes there will be no clear information on the RAM module other than the name of the module itself. But the module cannot be removed, since it is under warranty. But by the name you can understand what kind of memory it is. For example
Kingston KHX1600 C9D3 X2K2/8G X, all this means:
KHX 1600 -> RAM operates at 1600 MHz
C9 -> Timings (Delays) 9-9-9
D3 -> RAM type DDR3
8G X -> Volume 4 GB.
You can simply type the name of the module in search engines and you will find out all the information about it.
For example, information from the AIDA64 program about my RAM. Kingston HyperX RAM modules are installed in RAM slots 2 and 4, memory type DDR3, frequency 1600 MHz
DIMM2: Kingston HyperX KHX1600C9D3/4GX DDR3-1600 DDR3 SDRAM
DIMM4: Kingston HyperX KHX1600C9D3/4GX DDR3-1600 DDR3 SDRAM
Is it possible to install RAM sticks with different frequencies into a computer?
The RAM frequency does not have to be the same. The motherboard will set the frequency for all installed RAM sticks according to the slowest module. But I want to say that often a computer with brackets of different frequencies is unstable.
Let's do a simple experiment. For example, let's take my computer, it has two identical Kingston HyperX RAM modules, memory type DDR3, frequency 1600 MHz.
If I run the AIDA64 program on my Windows 8, it will show the following information (see the following screenshot). That is, the program AIDA64 shows simple technical characteristics of each RAM stick; in our case, both sticks have a frequency1600 MHz. But the programAIDA64 does not show at what frequency the RAM modules are currently operating; this needs to be looked at in another program called CPU-Z.
If you run the free CPU-Z program and go to the Memory tab, it will show you exactly what frequency your RAM sticks are running at. My memory operates in dual-channel Dual mode, frequency 800 MHz, since the memory is DDR3, its effective (double) speed is 1600 MHz. This means that my RAM sticks operate exactly at the frequency for which they are designed: 1600 MHz. But what will happen if next to your RAM strips operating at a frequency 1600 MHz I will set another bar with frequency 1333 MHz!?
Let's install an additional DDR3 memory stick in my system unit, operating at a lower frequency of 1333 MHz.
Let's look at what AIDA64 shows, the program shows that an additional 4 GB stick is installed, with a frequency of 1333 MHz.
Now let’s run the CPU-Z program and see at what frequency all three sticks operate. As we can see, the frequency is 668.7 MHz, since the memory is DDR3, its effective (double) speed is 1333 MHz.
That is, the motherboard automatically set the operating frequency of all RAM sticks to the slowest module at 1333 MHz.
It is not advisable to install RAM sticks in your computer with a frequency higher than what the motherboard supports. For example, if your motherboard supports a maximum RAM frequency of 1600 MHz, and you installed a RAM module operating at a frequency of 1866 on your computer, then in the best case, this module will operate at a lower frequency of 1600 MHz, and in the worst case, the module will operate at its frequency 1866 MHz, but the computer will periodically reboot itself or you will receive when you boot your computer blue screen, in this case you will have to enter the BIOS and manually set the RAM frequency to 1600 MHz.
Timings(signal delay) determine how often the processor can access RAM. If you have a quad-core processor and it has a large second-level cache, then too long timings are not a problem, since the processor accesses RAM less often. Is it possible to install RAM sticks with different timings in a computer? The timings also do not have to match. The motherboard will automatically set timings for all modules according to the slowest module.
What conditions are needed for my memory to work in dual-channel mode? Before buying RAM, you need to study as much information as possible about the motherboard. All information about your motherboard can be found in the manual that came with it upon purchase. If the manual is lost, you need to go to the official website of your motherboard. You will also find the article “How to find out the model and all information about your motherboard” useful.Most often these days there are motherboards that support the RAM operating modes described below. Dual Mode (two-channel mode, most common)– if you look closely at the motherboard, you can see that the RAM slots are colored different colors. This was done on purpose and means that the motherboard supports dual-channel RAM operation. That is, two RAM modules with the same characteristics (frequency, timings) and the same volume are specially selected and installed in RAM slots of the same color.
If your computer has one stick of RAM installed, but the motherboard supports dual-channel mode, you can buy an additional stick of RAM of exactly the same frequency and capacity and install both sticks in DIMM slots of the same color.
Is there an advantage to dual channel mode over single channel mode?
During normal work on a computer, you will not notice the difference, but when working in applications that actively use RAM, such as Adobe Premiere Pro (video editing), (Canopus) ProCoder (video encoding), Photoshop (working with images), games, the difference can be feel.
Note: Some motherboards will operate in dual-channel mode even if you install RAM modules of different sizes in the same color DIMM slots. For example, you will install a 512MB module in the first DIMM slot, and a 1GB stick in the third slot. The motherboard activates dual-channel mode for the entire volume of the first 512MB stick, and for the second stick (interestingly) also 512MB, and the remaining 512MB of the second stick will work in single-channel mode.
How do I know if my RAM is working in dual channel mode or not? Download the free CPU-Z program and go to the Memory tab, look at the Channel parameter in our case - Dual, which means the RAM operates in dual-channel mode. If the Channels parameter is Single, then the RAM operates in single-channel mode.
My opinion is that during normal work on a computer they will work the same, I personally didn’t notice much of a difference. I worked for a long time on a computer with one large stick of RAM and the performance was the same as on exactly the same computer with two sticks of RAM running in dual-channel mode. A survey of friends and acquaintances of system administrators confirmed me in this opinion. But when working with programs that actively use RAM, for example Adobe Premiere Pro, Canopus ProCoder, Photoshop, games, a computer with two sticks of RAM will work faster.
Of course it is possible, but not advisable. The computer will work more stable if it implements the RAM operating mode recommended in the motherboard data sheet. For example, two-channel mode.
Double Data Rate Synchronous Dynamic Random Access Memory - synchronous dynamic memory with random access and double data transfer rate) - a type of computer memory used in computing as RAM and video memory. It replaced SDRAM type memory.When using DDR SDRAM, twice the operating speed is achieved than in SDRAM, due to reading commands and data not only on the edge, as in SDRAM, but also on the fall of the clock signal. This doubles the data transfer rate without increasing the memory bus clock frequency. Thus, when DDR operates at a frequency of 100 MHz, we will get an effective frequency of 200 MHz (when compared with the analogue SDR SDRAM). The JEDEC specification makes a note that it is incorrect to use the term “MHz” in DDR; the correct rate is “millions of transfers per second per data pin.”
The specific operating mode of memory modules is dual-channel mode.
Description
DDR SDRAM memory chips are produced in TSOP packages and (later mastered) BGA (FBGA) packages, manufactured according to 0.13 and 0.09-micron process standards:
- IC supply voltage: 2.6 V +/- 0.1 V
- Power consumption: 527 mW
- I/O Interface: SSTL_2
The memory bus width is 64 bits, that is, 8 bytes are simultaneously transferred along the bus in one clock cycle. As a result, we obtain the following formula for calculation maximum speed transfers for a given memory type: ( memory bus clock speed)x 2 (data transfer twice per clock) x 8 (number of bytes transmitted per clock cycle). For example, to ensure data transfer twice per clock cycle, a special “2n Prefetch” architecture is used. The internal data bus is twice as wide as the external one. When transmitting data, the first half of the data bus is transmitted first on the rising edge of the clock signal, and then the second half of the data bus on the falling edge.
In addition to double data transfer, DDR SDRAM has several other fundamental differences from simple SDRAM. Basically, they are technological. For example, a QDS signal has been added and is located on the PCB along with the data lines. It is used for synchronization during data transfer. If two memory modules are used, then the data from them arrives at the memory controller with a slight difference due to the different distance. A problem arises in choosing a clock signal for reading them, and the use of QDS successfully solves this.
JEDEC sets standards for DDR SDRAM speeds, divided into two parts: the first for memory chips, and the second for memory modules, which, in fact, house the memory chips.
Memory chips
Each DDR SDRAM module contains several identical DDR SDRAM chips. For modules without error correction (ECC) their number is a multiple of 4, for modules with ECC the formula is 4+1.
Memory chip specification
- DDR200: DDR SDRAM type memory operating at 100 MHz
- DDR266: DDR SDRAM type memory operating at 133 MHz
- DDR333: DDR SDRAM type memory operating at 166 MHz
- DDR400: DDR SDRAM type memory operating at 200 MHz
Chip characteristics
- Chip capacity ( DRAM density). Recorded in megabits, for example, 256 Mbit - a chip with a capacity of 32 megabytes.
- Organization ( DRAM organization). It is written as 64M x 4, where 64M is the number of elementary storage cells (64 million), and x4 (pronounced “by four”) is the bit capacity of the chip, that is, the bit capacity of each cell. DDR chips come in x4 and x8, the latter are cheaper per megabyte of capacity, but do not allow the use of Chipkill, memory scrubbing and Intel SDDC functions.
Memory modules
DDR SDRAM modules are made in the DIMM form factor. Each module contains several identical memory chips and an SPD configuration chip. Registered memory modules also contain register chips that buffer and amplify the signal on the bus; non-registered memory modules do not have them.
Module characteristics
- Volume. Specified in megabytes or gigabytes.
- Number of chips ( # of DRAM Devices). A multiple of 8 for modules without ECC, a multiple of 9 for modules with ECC. Chips can be located on one or both sides of the module. The maximum number that fits on a DIMM is 36 (9x4).
- Number of rows (ranks) ( # of DRAM rows (ranks)).
The chips, as can be seen from their characteristics, have a 4- or 8-bit data bus. To provide higher bandwidth (e.g. DIMM requires 64 bits and 72 bits for ECC memory), chips are linked into ranks. The memory rank is common bus addresses and complementary data lines. One module can accommodate several ranks. But if you need more memory, then you can add ranks further by installing several modules on one board and using the same principle: all ranks sit on the same bus, only the select chips are different - each has its own. A large number of ranks electrically loads the bus, or more precisely the controller and memory chips, and slows down their operation. Hence, they began to use multi-channel architecture, which also allows independent access to several modules.
- Delays (timings): CAS Latency (CL), Clock Cycle Time (tCK), Row Cycle Time (tRC), Refresh Row Cycle Time (tRFC), Row Active Time (tRAS).
The characteristics of the modules and the chips they consist of are related.
The volume of the module is equal to the product of the volume of one chip and the number of chips. When using ECC, this number is further multiplied by a factor of 9/8, since there is one bit of error control redundancy per byte. Thus, the same memory module capacity can be filled with a large number (36) of small chips or a small number (9) of larger chips.
The total capacity of the module is equal to the product of the capacity of one chip by the number of chips and is equal to the product of the number of ranks by 64 (72) bits. Thus, increasing the number of chips or using x8 chips instead of x4 leads to an increase in the number of module ranks.
This example compares possible layouts of a 1 GB server memory module. Of the presented options, you should prefer the first or third, since they use x4 chips that support advanced error correction and failure protection methods. If you need to use peer-to-peer memory, only the third option remains available, but depending on the current cost of 256 Mbit and 512 Mbit chips, it may turn out to be more expensive than the first.
Memory module specification
| Specification | Memory bus clock speed | Maximum Theoretical Memory Bandwidth | |
|---|---|---|---|
| in single channel mode | in two-channel mode | ||
| PC1600* (DDR200) |
100 MHz | 1600 MB/sec | 3200 MB/sec |
| PC2100* (DDR266) |
133 MHz | 2133 MB/sec | 4267 MB/sec |
| PC2400 (DDR300) |
150 MHz | 2400 MB/sec | 4800 MB/sec |
| PC2700* (DDR333) |
166 MHz | 2667 MB/sec | 5333 MB/sec |
| PC3200* (DDR400) |
200 MHz | 3200 MB/sec | 6400 MB/sec |
| PC3500 (DDR433) |
217 MHz | 3467 MB/sec | 6933 MB/sec |
| PC3700 (DDR466) |
233 MHz | 3733 MB/sec | 7467 MB/sec |
| PC4000 (DDR500) |
250 MHz | 4000 MB/sec | 8000 MB/sec |
| PC4200 (DDR533) |
267 MHz | 4267 MB/sec | 8533 MB/sec |
Note 1: standards marked with an “*” are officially certified by JEDEC. The remaining types of memory are not certified by JEDEC, although they were produced by many memory manufacturers, and most of those produced in Lately motherboards supported these memory types.
Note 2: Memory modules were produced that operated at higher frequencies (up to 350 MHz, DDR700), but these modules were not in great demand and were produced in small volumes; in addition, they had a high price.
Module sizes are also standardized by JEDEC.
It should be noted that there is no difference in the architecture of DDR SDRAM with different frequencies, for example, between PC1600 (operating at 100 MHz) and PC2100 (operating at 133 MHz). The standard simply says at what guaranteed frequency this module operates.
DDR SDRAM memory modules can be distinguished from regular SDRAM by the number of pins (184 pins for DDR modules versus 168 pins for modules with regular SDRAM) and by the key (cutouts in the pad area) - SDRAM has two, DDR has one. According to JEDEC, DDR400 modules operate at a supply voltage of 2.6 V, and all slower modules operate at a voltage of 2.5 V. Some high-speed modules operate at higher voltages, up to 2.9 V, to achieve high frequencies.
Most of the latest chipsets with DDR support allowed the use of DDR SDRAM modules in dual-channel mode, and some chipsets in quad-channel mode. This method allows you to increase the theoretical bandwidth of the memory bus by 2 or 4 times, respectively. For memory to operate in dual-channel mode, 2 (or 4) memory modules are required; it is recommended to use modules operating at the same frequency and having the same capacity and timings (even better to use absolutely identical modules).
Now DDR modules have been practically replaced by modules of the DDR2 and DDR3 types, which, as a result of some changes in the architecture, make it possible to obtain greater bandwidth of the memory subsystem. Previously, the main competitor of DDR SDRAM was RDRAM memory (Rambus), but due to the presence of some shortcomings, over time it was practically forced out of the market.
Notes
Literature
V. Solomenchuk, P. Solomenchuk PC hardware. - 2008. - ISBN 978-5-94157-711-8
Guk M. Yu. IBM PC hardware. Encyclopedia. - Peter, 2006. - 1072 p.
Kopeikin M. V., Spiridonov V. V., Shumova E. O. Organization of computers and systems. (Computer memory): Textbook. Benefit. - St. Petersburg, 20064. - 153 p.
Links
- Description and illustration of almost all DDR memory parameters (Russian)
- Intel® Server Board SE7501CW2 Memory List Test Report Summary (PDF, 246,834 bytes) (English) - a small list of possible memory module configurations.
- Kingston's Literature Page - several reference documents describing the organization of memory modules.
| Types of Dynamic Random Access Memory (DRAM) | |
|---|---|
| Asynchronous | FPM RAM · EDO RAM |
| Synchronous | SDRAM · DDR SDRAM · Mobile DDR (LPDDR) · DDR2 SDRAM · DDR3 SDRAM · DDR4 SDRAM |
| Graphic | |
Memory: RAM, DDR SDRAM, SDR SDRAM, PC100, DDR333, PC3200... how to figure it all out? Let's try!
So, the first thing we must do is “smooth out” all the doubts and questions about the denominations in memory...
The most common types of memory are:
- SDR SDRAM(designations PC66, PC100, PC133)
- DDR SDRAM(designations PC266, PC333, etc. or PC2100, PC2700)
- RDRAM(PC800)
Now for subsequent explanations, I’ll tell you about timings and frequencies. Timing- this is the delay between individual operations performed by the controller when accessing memory.
If we consider the composition of the memory, we get: its entire space is presented in the form of cells (rectangles), which consist of a certain number of rows and columns. One such "rectangle" is called a page, and the collection of pages is called a bank.
To access a cell, the controller sets the bank number, the page number in it, the row number and the column number, time is spent on all requests, in addition, quite a large cost is spent on opening and closing the bank after the read/write operation itself. Every action takes time, it is called timing.
Now let's take a closer look at each of the timings. Some of them are not available for configuration - access time CS# (crystal select) this signal determines the crystal (chip) on the module to carry out the operation.
In addition, the rest can be changed:
- RCD (RAS-to-CAS Delay) this is the delay between signals RAS (Row Address Strobe) And CAS (Column Address Strobe), this parameter characterizes the interval between accesses to the bus by the signal memory controller RAS# And CAS#.
- CAS Latency (CL) this is the delay between the read command and the availability of the first word to be read. Introduced to set address registers to guarantee a stable signal level.
- RAS Precharge (RP) this is the time of re-issuance (charge accumulation period) of the RAS# signal - after what time the memory controller will be able to issue the line address initialization signal again.
- Precharge Delay(or Active Precharge Delay; more often referred to as Tras) is the active time of the line. Those. the period during which a row is closed if the next required cell is in another row.
- SDRAM Idle Timer(or SDRAM Idle Cycle Limit) the number of clock cycles during which the page remains open, after which the page is forced to close, either to access another page or to refresh (refresh)
- Burst Length This is a parameter that sets the size of the memory prefetch relative to the starting address of the access. The larger its size, the higher the memory performance.
Note: the order of operations is exactly this (RCD-CL-RP), but often timings are written not in order, but by “importance” - CL-RCD-RP.
Well, we seem to have understood the basic concepts of timings, now let’s take a closer look at memory ratings (PC100, PC2100, DDR333, etc.)
There are two types of designations for the same memory: one by the "effective frequency" DDRxxx, and the second by the theoretical bandwidth PCxxxx.
The designation "DDRxxx" historically developed from the sequence of names of the standards "PC66-PC100-PC133" - when it was customary to associate memory speed with frequency (unless a new abbreviation "DDR" was introduced in order to distinguish SDR SDRAM from DDR SDRAM). Simultaneously with DDR SDRAM memory, RDRAM memory (Rambus) appeared, on which cunning marketers decided to set not the frequency, but the bandwidth - PC800. At the same time, the width of the data bus remained 64 bits (8 bytes), that is, those same PC800 (800 MB/s) were obtained by multiplying 100 MHz by 8. Naturally, nothing has changed from the name, and PC800 RDRAM is the same the same PC100 SDRAM, only in a different package... This is nothing more than a sales strategy, roughly speaking, “to trick people”. In response, companies that produce modules began to write theoretical throughput - PCxxxx. This is how PC1600, PC2100 and the following appeared... At the same time, DDR SDRAM has an effective frequency that is twice as high, which means the number on the designation is higher.
Here is an example of notation correspondence:
- 100 MHz = PC1600 DDR SDRAM = DDR200 SDRAM = PC100 SDRAM = PC800 RDRAM
- 133 MHz = PC2100 DDR SDRAM = DDR266 SDRAM = PC133 SDRAM = PC1066 RDRAM
- 166 MHz = PC2700 DDR SDRAM = DDR333 SDRAM = PC166 SDRAM = PC1333 RDRAM
- 200 MHz = PC3200 DDR SDRAM = DDR400 SDRAM = PC200 SDRAM = PC1600 RDRAM
- 250 MHz = PC4000 DDR SDRAM = DDR500 SDRAM
As for RAMBUS (RDRAM) I won’t write much, but I’ll still try to introduce it to you.
There are three types of RDRAM - Base, Concurrent And Direct. Base and Concurrent are practically the same thing, but Direct has significant differences, so I’ll tell you about the first two in general, and about the last one in more detail.
Base RDRAM And Concurrent RDRAM Basically they differ only in operating frequencies: for the first, the frequency is 250-300 MHz, and for the second, this parameter is, accordingly, 300-350 MHz. Data is transmitted at two data packets per clock cycle, so the effective transmission frequency is twice as high. The memory uses an eight-bit data bus, which consequently gives a throughput of 500-600 Mb/s (BRDRAM) and 600-700 Mb/s (CRDRAM).
Direct RDRAM (DRDRAM) unlike Base and Concurrent, it has a 16-bit bus and operates at a frequency of 400 MHz. The bandwidth of Direct RDRAM is 1.6 Gb/s (taking into account bidirectional data transfer), which looks pretty good compared to SDRAM (1 Gb/s for PC133). Usually, when talking about RDRAM, they mean DRDRAM, so the letter "D" in the name is often omitted. When this type of memory appeared, Intel created a chipset for the Pentium 4 - i850.
The biggest plus Rambus memory means that the more modules, the greater the throughput, for example, up to 1.6 Gb/s per channel and up to 6.4 Gb/s with four channels.
There are also two disadvantages, quite significant:
1. The claws are gold and become unusable if the memory card is pulled out and inserted into the slot more than 10 times (approximately).
2. Overpriced, but many people find very good use for this memory and are willing to pay top dollar for them.
That's probably all, we've figured out the timings, names and denominations, now I'll tell you a little about various important little things.
You probably saw the By SPD option in the BIOS when setting the memory frequency, what does this mean? SPD - Serial Presence Detect, this is a microcircuit on the module into which all the parameters for the operation of the module are programmed, these are the “default values”, so to speak. Now, due to the emergence of “noname” companies, they began to write the manufacturer’s name and date into this chip.
Register memory
Registered Memory This is memory with registers that serve as a buffer between the memory controller and the module chips. Registers reduce the load on the synchronization system and allow you to add a very large amount of memory (16 or 24 gigabytes) without overloading the controller circuits.
But this scheme has a drawback - the registers introduce a delay of 1 clock cycle for each operation, which means that register memory is slower than usual, all other things being equal. That is, the overclocker is not interested in it (and it is very expensive).
Everyone is now shouting about Dual channel - what is it?
Dual channel- double channel, this allows you to access two modules simultaneously. Dual channel is not a type of module, but a function integrated into the motherboard. Can be used with two (preferably) identical modules. It turns on automatically when there are 2 modules.
Note: To activate this function, you need to install modules in slots of different colors.
Parity and ECC
Memory with Parity This is a parity-check memory that can detect certain types of errors.
Memory with ECC This is an error correction memory that allows you to find and correct the error of one bit in a byte. Mainly used on servers.
Note: it is slower than usual, not suitable for people who love speed.
I hope that after reading the article you have understood the more popular “obscure concepts”.
Now, having learned what it is and what and how it serves, many of you are probably thinking about purchasing a more powerful and productive RAM for your computer. After all, increasing computer performance with additional memory RAM is the simplest and cheapest (unlike, for example, a video card) method of upgrading your pet.
And... Here you are standing at the display case with packages of RAMs. There are many of them and they are all different. Questions arise: Which RAM should I choose?How to choose the right RAM and not make a mistake?What if I buy a RAM and then it doesn’t work? These are completely reasonable questions. In this article I will try to answer all these questions. As you already understand, this article will take its rightful place in the series of articles in which I wrote about how to choose the right individual computer components, i.e. iron. If you haven't forgotten, it included the following articles:
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This cycle will continue, and in the end you will be able to assemble for yourself a super computer that is perfect in every sense 🙂 (if finances allow, of course :))
In the meantime learning how to choose the right RAM for your computer.
Go!
RAM and its main characteristics.
When choosing RAM for your computer, you must take into account your motherboard and processor because RAM modules are installed on the motherboard and it also supports certain types of RAM. This creates a relationship between the motherboard, processor and RAM.
Find out about what RAM does your motherboard and processor support? You can go to the manufacturer’s website, where you need to find the model of your motherboard, as well as find out which processors and RAM it supports. If you don’t do this, it will turn out that you bought a super modern RAM, but it is not compatible with your motherboard and will gather dust somewhere in your closet. Now let's move directly to the main technical characteristics of RAM, which will serve as unique criteria when choosing RAM. These include:
Here I have listed the main characteristics of RAM that you should pay attention to first when purchasing it. Now we will reveal each of them in turn.
Type of RAM.
Today, the most preferred type of memory in the world is memory modules DDR(double data rate). They differ in release time and, of course, technical parameters.
- DDR or DDR SDRAM(translated from English: Double Data Rate Synchronous Dynamic Random Access Memory - synchronous dynamic memory with random access and double data transfer rate). Modules of this type have 184 contacts on the strip, are powered by a voltage of 2.5 V and have a clock frequency of up to 400 megahertz. This type of RAM is already obsolete and is used only in old motherboards.
- DDR2- a type of memory that is widespread at this time. It has 240 contacts on the printed circuit board (120 on each side). Consumption, unlike DDR1, is reduced to 1.8 V. The clock frequency ranges from 400 MHz to 800 MHz.
- DDR3- the leader in performance at the time of writing this article. It is no less common than DDR2 and consumes 30-40% less voltage compared to its predecessor (1.5 V). Has a clock frequency of up to 1800 MHz.
- DDR4- new, super modern type RAM, ahead of its counterparts both in performance (clock frequency) and voltage consumption (and therefore characterized by lower heat generation). Support for frequencies from 2133 to 4266 MHz is announced. On this moment These modules have not yet entered mass production (they promise to release them into mass production in mid-2012). Officially, fourth generation modules operating in DDR4-2133 at a voltage of 1.2 V were presented at CES by Samsung on January 4, 2011.
Amount of RAM.
I won’t write much about memory capacity. Let me just say that it is in this case that size matters :)
Just a few years ago, RAM of 256-512 MB satisfied all the needs of even cool gaming computers. At present, for normal functioning, only the operating room is separate windows systems 7 requires 1 GB of memory, not to mention applications and games. There will never be too much RAM, but I’ll tell you a secret that 32-bit Windows uses only 3.25 GB of RAM, even if you install all 8 GB of RAM. You can read more about this.
Dimensions of the planks or the so-called Form factor.
Form - factor- these are the standard sizes of RAM modules, the type of design of the RAM strips themselves.
DIMM(Dual InLine Memory Module - a double-sided type of module with contacts on both sides) - mainly intended for desktop desktop computers, and SO-DIMM used in laptops.
Clock frequency.
This is a fairly important technical parameter of RAM. But the motherboard also has a clock frequency, and it is important to know the operating bus frequency of this board, since if you bought, for example, a RAM module DDR3-1800, and the motherboard slot (connector) supports the maximum clock frequency DDR3-1600, then the RAM module as a result will operate at a clock frequency of 1600 MHz. In this case, all sorts of failures, errors in the operation of the system, etc. are possible.
Note: Memory bus frequency and processor frequency are completely different concepts.
From the tables above, you can understand that the bus frequency, multiplied by 2, gives the effective memory frequency (indicated in the “chip” column), i.e. gives us the data transfer speed. The name tells us the same thing. DDR(Double Data Rate) - which means double the data transfer rate.
For clarity, I will give an example of decoding in the name of the RAM module - Kingston/PC2-9600/DDR3(DIMM)/2Gb/1200MHz, Where:
—Kingston- manufacturer;
- PC2-9600— name of the module and its capacity;
- DDR3(DIMM)— memory type (form factor in which the module is made);
— 2Gb— module volume;
- 1200MHz— effective frequency, 1200 MHz.
Bandwidth.
Bandwidth- a memory characteristic on which system performance depends. It is expressed as the product of the system bus frequency and the amount of data transferred per clock cycle. Throughput (peak data rate) is a comprehensive measure of capability RAM, it takes into account transmission frequency, bus width and the number of memory channels. The frequency indicates the potential of the memory bus per clock cycle - at a higher frequency, more data can be transferred.
The peak indicator is calculated using the formula: B=f*c, Where:
B is the bandwidth, f is the transmission frequency, c is the bus width. If you use two channels to transmit data, we multiply everything received by 2. To get a figure in bytes/s, you need to divide the result by 8 (since there are 8 bits in 1 byte).
For better performance RAM bus bandwidth And processor bus bandwidth must match. For example, for Intel processor core 2 duo E6850 with a system bus of 1333 MHz and a bandwidth of 10600 Mb/s, you can install two modules with a bandwidth of 5300 Mb/s each (PC2-5300), in total they will have a system bus bandwidth (FSB) equal to 10600 Mb /s.
Bus frequency and bandwidth are denoted as follows: “ DDR2-XXXX" And " PC2-YYYY". Here "XXXX" denotes the effective memory frequency, and "YYYY" the peak bandwidth.
Timings (latency).
Timings (or latency) are the time delays of the signal, which, in technical specifications RAM is written as " 2-2-2 " or " 3-3-3 " etc. Each number here expresses a parameter. In order it is always " CAS Latency"(working cycle time), " RAS to CAS Delay"(full access time) and " RAS Precharge Time» (pre-charge time).
Note
So that you can better understand the concept of timings, imagine a book, it will be our RAM that we access. Information (data) in a book (RAM) is distributed among chapters, and chapters consist of pages, which in turn contain tables with cells (like in Excel tables, for example). Each cell with data on the page has its own vertical (columns) and horizontal (rows) coordinates. To select a row, the RAS (Raw Address Strobe) signal is used, and to read a word (data) from the selected row (i.e., to select a column), the CAS (Column Address Strobe) signal is used. The full reading cycle begins with the opening of the “page” and ends with its closing and recharging, because otherwise the cells will be discharged and the data will be lost. This is what the algorithm for reading data from memory looks like:
- the selected "page" is activated by applying the RAS signal;
- data from the selected line on the page is transmitted to the amplifier, and a delay is required for data transmission (it is called RAS-to-CAS);
- a CAS signal is given to select a (column) word from that row;
- data is transferred to the bus (from where it goes to the memory controller), and a delay also occurs (CAS Latency);
- following the word goes without delay, since it is contained in the prepared line;
- after access to the row is completed, the page is closed, the data is returned to the cells and the page is recharged (the delay is called RAS Precharge).
Each number in the designation indicates how many bus cycles the signal will be delayed. Timings are measured in nanoseconds. The numbers can have values from 2 to 9. But sometimes a fourth one is added to these three parameters (for example: 2-3-3-8), called “ DRAM Cycle Time Tras/Trc” (characterizes the performance of the entire memory chip as a whole).
It happens that sometimes a cunning manufacturer indicates only one value in the RAM characteristics, for example “ CL2"(CAS Latency), the first timing is equal to two clock cycles. But the first parameter does not have to be equal to all timings, and may be less than others, so keep this in mind and do not fall for the manufacturer’s marketing ploy.
An example to illustrate the impact of timings on performance: a system with memory at 100 MHz with 2-2-2 timings has approximately the same performance as the same system at 112 MHz, but with 3-3-3 timings. In other words, depending on latency, the performance difference can be as much as 10%.
So, when choosing, it is better to buy memory with the lowest timings, and if you want to add a module to an already installed one, then the timings of the purchased memory must match the timings of the installed memory.
Memory operating modes.
RAM can operate in several modes, if of course such modes are supported by the motherboard. This single channel, two-channel, three-channel and even four-channel modes. Therefore, when choosing RAM, you should pay attention to this module parameter.
Theoretically, the speed of operation of the memory subsystem in dual-channel mode increases by 2 times, in three-channel mode - by 3 times, respectively, etc., but in practice, in dual-channel mode, the performance increase, unlike single-channel mode, is 10-70%.
Let's take a closer look at the types of modes:
- Single channel mode(single-channel or asymmetric) – this mode is activated when only one memory module is installed in the system or all modules differ from each other in memory capacity, operating frequency or manufacturer. It doesn’t matter what slots or memory you install into. All memory will run at the speed of the slowest memory installed.
- Dual Mode(dual-channel or symmetrical) - the same amount of RAM is installed in each channel (and theoretically the maximum data transfer rate is doubled). In dual-channel mode, memory modules work in pairs: 1st with 3rd and 2nd with 4th.
- Triple Mode(three-channel) – the same amount of RAM is installed in each of the three channels. Modules are selected according to speed and volume. To enable this mode, modules must be installed in slots 1, 3 and 5/or 2, 4 and 6. In practice, by the way, this mode is not always more productive than the two-channel one, and sometimes even loses to it in data transfer speed.
- Flex Mode(flexible) – allows you to increase the performance of RAM when installing two modules of different sizes, but the same operating frequency. As in dual-channel mode, memory cards are installed in the same connectors of different channels.
Generally, the most common option is dual-channel memory mode.
To operate in multi-channel modes, there are special sets of memory modules - the so-called Kit memory(Kit set) - this set includes two (three) modules, from the same manufacturer, with the same frequency, timings and memory type.
Appearance of KIT kits:
for dual channel mode
for three-channel mode
But the most important thing is that such modules are carefully selected and tested by the manufacturer itself to work in pairs (triples) in two- (three-) channel modes and do not imply any surprises in operation and configuration.
Manufacturer of modules.
Now on the market RAM Such manufacturers as have proven themselves well: Hynix, amsung, Corsair, Kingmax, Transcend, Kingston, OCZ…
Each company has its own for each product marking number, from which, if deciphered correctly, you can learn a lot for yourself useful information about the product. Let's try to decipher the module marking as an example Kingston families ValueRAM(see image):
Explanation:
- KVR– Kingston ValueRAM i.e. manufacturer
- 1066/1333 – operating/effective frequency (Mhz)
- D3- memory type (DDR3)
- D (Dual) – rank/rank. A dual-rank module is two logical modules wired onto one physical channel and alternately using the same physical channel (needed to achieve the maximum amount of RAM with a limited number of slots)
- 4 – 4 DRAM memory chips
- R – Registered, indicates stable operation without failures or errors for as long a continuous period of time as possible
- 7 – signal delay (CAS=7)
- S– temperature sensor on the module
- K2– set (kit) of two modules
- 4G– the total volume of the kit (both slats) is 4 GB.
Let me give you another example of marking CM2X1024-6400C5:
From the labeling it is clear that this is DDR2 module volume 1024 MB standard PC2-6400 and delays CL=5.
Stamps OCZ, Kingston And Corsair recommended for overclocking, i.e. have the potential for overclocking. They will have small timings and a clock frequency reserve, plus they are equipped with radiators, and some even coolers for heat removal, because When overclocking, the amount of heat increases significantly. The price for them will naturally be much higher.
I advise you not to forget about fakes (there are a lot of them on the shelves) and buy RAM modules only in serious stores that will give you a guarantee.
Finally:
That's all. With the help of this article, I think you will no longer be mistaken when choosing RAM for your computer. Now you can choose the right RAM for the system and increase its performance without any problems. Well, for those who will buy RAM (or have already bought it), I will dedicate the following article, in which I will describe in detail how to install RAM correctly into the system. Do not miss…
Best RAM 2019
Corsair Dominator Platinum
The best memory among its classmates with high performance and innovation in RGB technology. DDR4 standard, speed 3200MHz, default timings 16.18.18.36, two 16 GB modules. The strips have bright Capellix RGB LED backlights, an advanced iCUE program, and Dominator DHX heat sinks. The only problem is that the height of the module may not be suitable.
Corsair, as always, outdoes itself with each new model, and the Dominator Platinum is no exception. Today it is the favorite DDR4 memory kit for gamers and owners of powerful workstations. The appearance of the modules is sleek and stylish to appeal to gaming enthusiasts, DHX cooling works efficiently, and the performance of the slats is ready to become a legend. In any case, it will provide the user with flagship parameters for many years. Now the memory has a new design, a new, brighter Corsair Capellix backlight with 12 LEDs. Software(proprietary) iCUE provides flexible memory tuning for maximum performance. If you changed the motherboard or processor, or maybe graphics accelerator, for any new component the memory can be configured as native.
The price tag of the memory is slightly higher than that of other manufacturers, but this is compensated by the highest quality and amazing performance.
There are several common types of memory modules used in modern computers and computers that were released a few years ago but still work in homes and offices.
For many users, distinguishing them both in appearance and performance is a big problem.
In this article we will look at the main features of different memory modules.
FPM
FPM (Fast Page Mode) is a type of dynamic memory.
Its name corresponds to the principle of operation, since the module allows faster access to data that is on the same page as the data transferred during the previous cycle.
These modules were used on most 486-based computers and early Pentium-based systems around 1995.
EDO
EDO (Extended Data Out) modules appeared in 1995 as a new type of memory for computers with Pentium processors.
This is a modified version of FPM.
Unlike its predecessors, EDO begins fetching the next block of memory at the same time it sends the previous block to the CPU.
SDRAM
SDRAM (Synchronous DRAM) is a type of random access memory that works so fast that it can be synchronized with the processor frequency, excluding standby modes.
The microcircuits are divided into two blocks of cells so that while accessing a bit in one block, preparations are in progress for accessing a bit in another block.
If the time to access the first piece of information was 60 ns, all subsequent intervals were reduced to 10 ns.
Starting in 1996, most Intel chipsets began to support this type of memory module, making it very popular until 2001.
SDRAM can operate at 133 MHz, which is almost three times faster than FPM and twice as fast as EDO.
Most computers with Pentium and Celeron processors released in 1999 used this type of memory.
DDR
DDR (Double Data Rate) was a development of SDRAM.
This type of memory module first appeared on the market in 2001.
The main difference between DDR and SDRAM is that instead of doubling the clock speed to speed things up, these modules transfer data twice per clock cycle.
Now this is the main memory standard, but it is already beginning to give way to DDR2.
DDR2
DDR2 (Double Data Rate 2) is a newer variant of DDR that should theoretically be twice as fast.
DDR2 memory first appeared in 2003, and chipsets supporting it appeared in mid-2004.
This memory, like DDR, transfers two sets of data per clock cycle.
The main difference between DDR2 and DDR is the ability to operate at significantly higher clock speeds, thanks to improvements in design.
But the modified operating scheme, which makes it possible to achieve high clock frequencies, at the same time increases delays when working with memory.
DDR3
DDR3 SDRAM (double data rate synchronous dynamic random access memory, third generation) is a type of random access memory used in computing as RAM and video memory.
It replaced DDR2 SDRAM memory.
DDR3 has a 40% reduction in energy consumption compared to DDR2 modules, which is due to the lower (1.5 V, compared to 1.8 V for DDR2 and 2.5 V for DDR) power supply voltage of the memory cells.
Reducing the supply voltage is achieved through the use of a 90-nm (initially, later 65-, 50-, 40-nm) process technology in the production of microcircuits and the use of Dual-gate transistors (which helps reduce leakage currents).
DIMMs with DDR3 memory are not mechanically compatible with the same DDR2 memory modules (the key is located in a different location), so DDR2 cannot be installed in DDR3 slots (this is done to prevent the mistaken installation of some modules instead of others - these types of memory are not the same according to electrical parameters).
RAMBUS (RIMM)
RAMBUS (RIMM) is a type of memory that appeared on the market in 1999.
It is based on traditional DRAM, but with a radically changed architecture.
The RAMBUS design makes memory access more intelligent, allowing pre-access to data while slightly offloading the CPU.
The basic idea used in these memory modules is to receive data in small bursts but at a very high clock speed.
For example, SDRAM can transfer 64 bits of information at 100 MHz, and RAMBUS can transfer 16 bits at 800 MHz.
These modules did not become successful as Intel had many problems with their implementation.
RDRAM modules appeared in the Sony Playstation 2 and Nintendo 64 game consoles.
Translation: Vladimir Volodin