Computer ram Types and definition

The official RAM definition is: Random Access Memory is a volatile part of a computer system that temporarily stores input, output and intermediate data of programs and the operating system.

What is ram


What is Ram (Random access memory)

Unlike a storage device such as a hard disk, RAM has a high read and write speed. In addition, it is volatile – when you turn off the computer, data in RAM is not saved. But RAM is not intended for long-term storage of information. There are other devices for this (hard drive, flash drives, CDs, external hard drives ….). The main purpose of the computer’s random access memory is to quickly (quickly) read and write information, and temporarily store the data needed by the processor. The fact is that when reading data from the hard drive, they are first transferred to RAM and remain there for the time that the processor needs to process it.

Computer performance depends on the amount of RAM and its speed. The volume of modern RAM is measured in gigabytes (GB), and the speed in megahertz.

RAM is necessary for the temporary storage of data, which ensures the normal functioning of the software. Usually, its microcircuits are connected to the motherboard through the corresponding connectors. In general, the main task of RAM is to be a buffer between the processor and the hard disk while the computer is in operation.

imagine the situation You print the text in Word, but you have not yet reached the point of saving. In fact, it still in the RAM and will be cleared if we restart the computer, At this moment, the RAM is just storing the information. When you save your document and select a place to store it, it will be saved the hard drive memory. and restarting the computer won’t take that data away anymore.

In the process of starting the operating system, the RAM contains programs and OS data. The amount of RAM directly affects the solution of simultaneously running tasks. The more RAM, the more tasks the computer can process. It is also very often used by the video card as video memory.

We figured out what RAM is. But how is it arranged and what is it characterized by? In fact, the structure of RAM is similar to a set of bee honeycombs. Each cell stores a certain amount of data (1-4 bits). Note that each “cell” has its own personal address. It is subdivided into data on the location of horizontal construction (Row) and vertical position (Column).

Simply put, each cell is a capacitor that is capable of storing electrical discharge for a certain time. Thanks to special algorithms, the data recorded in this way are converted into a format that the computer understands. In addition, a signal of type RAS and CAS, respectively, is used to transmit the address of the row and/or vertical column of the cell. However, all this applies to such matters, which the ordinary user does not need to know about.

in simple language
A processor is the brain of a computer that processes all the information. A hard disk ( or SSD-drive ) stores all the data (programs, photos, movies, music …). Random access memory is an intermediate link between them.

Here, in principle, I answered the first questions. Although not, little is understood by the ordinary person from this definition. But now we will analyze everything in detail.

So The computer has several types of memory: non-volatile and volatile or temporary.

Non-volatile memory is any memory device that can store data regardless of whether power is supplied to it or not. In a computer, that is a hard drive. You can save a file on it, disconnect the computer from the power, and the next time you turn it on again, everything will remain in place.

Volatile memory is a computer memory that needs constant power to store information. Such in the computer is RAM. This means that if you turn off the power from it (turn off the computer), all the information stored in it will disappear. That is, every time you turn on the computer, its RAM is empty.

How does RAM work

During operation, the memory of the random access memory device is a temporary buffer, it stores temporary data, processes, etc., between disk drives and the central processor.

All information: video and audio files, text documents, images, and photographs are stored on disk media, usually it is a hard disk and to use the information, it is necessary that it be processed by the central processor. To speed up the process of loading and processing data by the processor, between it and the read-only memory, the intermediate link is the RAM, which many times increase the data transfer speed between these computer components.

If the information would bypass the random access memory represented in the computer by the memory modules (slats) and would be written directly to the hard disk, then each process would take much longer, because the exchange rate with the hard disk is very low compared to the speed exchange with RAM.

For a deeper understanding of temporary memory, the principle of which is used on a computer in RAM, you need to familiarize yourself with the examples below.

A good example would be a computer game. The newly installed game, while not running, is stored on the computer’s hard drive or solid-state drive, in any case in read-only memory, and is quietly waiting for launch. At this moment, a program such as a game does not consume RAM resources in the form of memory. As soon as the decision to start the game was made, in temporary memory, or to be more precise in the operational memory, many processes immediately started and so on in every program.

Another very obvious example would be cut out text in such an office program as Microsoft Word. As soon as a piece of text has been selected and cut, it appears in the clipboard of the running application and that is why we can not find it anywhere. The Word buffer itself is located in the computer’s RAM.

It is important to know that the RAM module is a volatile device and when you turn off or restart the computer, all stored information will irretrievably disappear, and you won’t be able to restore it just like on a hard disk.

How does it all work?

If you read carefully, you already realized that first the necessary information is downloaded from the hard drive, “stored” in the RAM modules, and then processed by the central processor. All these devices can communicate directly, but much more often this happens with the participation of the cache.

Both processors and hard drives have it. A cache is designed to store especially frequently used information. Its presence allows you to significantly speed up the performance of the entire system as a whole, since the speed of the hard drive and RAM is much lower than that of the central processor itself. If the volume of this drive is sufficient, it is possible to completely get rid of downtime and equipment inactivity.

The RAM itself is controlled by a separate controller, which is located on the north bridge of the motherboard. In addition, the connection of the central processor to other devices that use “bold” buses for data transfer (all the same RAM, graphics subsystem) depends on it.

When the RAM is working and information is being written to some cell, then all the data that was there before will be lost permanently. It should be noted that modern operating systems support the breakdown of RAM into several partitions at once, this provides a significantly increased speed. How does it all work?

The fact is that modern RAM devices have a large volume, and therefore they can contain data from several processes running simultaneously. Of course, the central processor is also capable of processing several hundred tasks at a time. To ensure normal functioning of the computer, a dynamic memory allocation system was developed. In this case, for each task that is currently “under consideration” by the central processor, its own, dynamically changing block of RAM is allocated.

Why such difficulties?

Such a unit helps to manage the available amount of RAM much more economically, since the most important and priority tasks are allocated more space. It should be noted that truly high-quality dynamic distribution is available only to users of the latest versions of operating systems.

In addition, the old distribution methods that were used during the time of Windows 98 or earlier systems made the programs of those years completely inoperative on modern versions of the OS. Even if you have “gigabyte 4” of RAM on board, the next-generation RAM will simply not understand the old instructions.

Possible operating modes

RAM can work in single-channel, two-, three- and four-channel modes. Definitely, if your motherboard has a sufficient number of slots, then it’s better to take several identical smaller volumes instead of one memory bar. The speed of access to them will grow from 2 to 4 times.

Ram Operating modes

For the memory to work in dual-channel mode, you need to install the slats in the same color slots on the motherboard. As a rule, the color is repeated through the connector. It is important that the memory frequency in the two slats be the same.

  • Single channel. Single-channel, asymmetric mode. It is turned on in two cases: when the system has only one memory card, or if the user has installed several microcircuits from different manufacturers that differ from each other in their parameters. It is important to note that the system in the second case will focus on the weakest RAM module, working at its frequency.
  • Dual mode Dual channel, balanced mode. To do this, two identical slots of RAM are installed in two slots, as a result of which the data transfer speed can significantly increase. Accordingly, to activate this mode, microcircuits must be set in 1 and 3 and / or 2 and 4 slots. Note that 2nd generation RAM (DDR2) can only work in this mode (most often).
  • Triple Mode. Three-channel mode in recent times is quite rare. In general, it is a variation of the previous mode, but it is used only on those motherboards on which there are three connectors for installing RAM modules. It should be noted that in practice this mode is very often inferior to the two-channel version (any test of RAM will indicate this).
  • Quad Mode – four-channel mode, which works on the principle of two-channel, respectively increasing the speed of 4 times. It is used where extremely high speed is needed – for example, in servers.
  • Flex Mode (flexible). This is a very interesting mode, which allows you to “squeeze” the maximum performance out of two different memory dies (it is important that they are the same in frequency). Installation of modules is carried out in the same manner as the two-channel version.

Why we need RAM?

This may raise the question, why do you need RAM at all? Is it possible to allocate a buffer on the hard disk for the temporary storage of data processed by the processor? In principle, it is possible, but it would be a very inefficient approach.

The physical device of RAM is such that reading/writing in it is much faster. If instead of RAM you had ROM, the computer would work very slowly.

The main characteristics of RAM

Type of RAM. You need to know what type of RAM your motherboard supports: DDR, DDR2, DDR3 or DDR4. And from this, build on further.

The amount of RAM. Here you need to build on your needs the more RAM you have on your computer, the more programs you can use at the same time. But still, I will give you a little hint. For a simple home or office computer, 4 GB is enough. If you have a gaming computer or you often use “heavy” professional programs, you can install from 8 or more GB of RAM.

Clock frequency

Inexperienced users are often limited by their volume when choosing RAM, but the memory frequency is no less important. It determines how fast data will be exchanged with the processor.

The bigger, the better. But here you also need to look to ensure that this frequency is supported by the motherboard and processor. Otherwise, if the RAM frequency is higher than that supported by the motherboard, the RAM will work at lower frequencies, which for you will mean overpaying for unnecessary performance.
Operates at frequencies

  • DDR – 400 MHz
  • DDR2 – 1200 MHz
  • DDR3 – 2400 MHz
  • DDR4 – 4200 MHz.
    The higher the clock speed, the faster the system.

Speaking about the frequency of the memory, it should be remembered that for one period of the clock frequency several pieces of data are read with a resulting frequency (FSB) several times higher than the clock: the quadruple clock frequency of 100 MHz is 400 MHz, and 133 MHz is 533 MHz. If two-channel memory is used, or one by one reading from two data banks, the resulting frequency can increase to 800 MHz. In addition to increasing the read/write frequency, memory modules also use other ways to improve performance. The most popular method is data buffering, when a chip is installed on the memory module for temporary storage of data in order to eliminate the time intervals during which the process of reading the next portion of data from the storage matrix takes place.

To some extent, the reliability of the data also affects the overall performance of the computer (in the error correction mode, the speed slows down, but the final performance may be higher). So, modules with ECC (Error Checking and Correction) technology contain one chip more than ordinary ones. In such modules, each data byte (8 bits) is equipped with one more bit for parity control in a byte (currently, the group method of data reliability is used when one error is automatically corrected, and a second error generates a failure signal in the group). Of course, the price of such memory modules is higher, therefore they are most often used in computers where high reliability is required, but in personal computers ordinary memory modules are used, because single memory errors have little effect on the operation of modern software. Memory modules are available in Registered DIMM (with data buffering) and Unbuffered DIMM (without data buffering) options with a different number of contacts for desktop and mobile computers.

Memory module timings

The “terrible” parameter of RAM, which few people know about and which is rarely taken into account when choosing a memory,
Determines the period of time from the moment of accessing the memory to receiving the requested information. The lower the timing value, the higher the RAM speed. Memory size and timing are interconnected. A larger module implies a longer memory access time. Installing multiple identical smaller DRAM slots helps solve the problem.

In order to read or write data in the dynamic memory chip, which are used in the computer’s RAM, you need to perform a number of operations. Generally speaking, first the chipset or processor gives the address of the desired storage cell, then there is the waiting time when the chip completes the process of selecting the desired cell and transferring information from it to the output buffer or writing to it one or zero, and bringing the storage cell and control circuits in the waiting state for the next call to it (there are actually more operations).

Each operation requires time – waiting cycles, and since the speed of the microcircuits is much lower than the clock frequency of the information buses, a number of digits are indicated for the dynamic memory microcircuits, for example, 3-2-3, 3-3-3-20 or 2-3 -2-6-1, which are called timing of the microcircuit or memory module. Each digit in the timing is the number of bus ticks for a particular operation. There are a lot of different operations when accessing memory cells, but users operate on a limited number. In particular, for modern memory modules, five operations or timings can be indicated, for example, 2-3-2-6-1. The decoding of this sequence is shown below.

Decoding of time delays (timing 2-3-2-6-1)

The most ideal case is when all timings are 1, for example, 1-1-1. But this can only be for a very low processor clock speed, equal to several hundred megahertz. In practice, timings are rarely close to the ideal case, for example: KHX4300D2 / 256 DDR2 memory module has a timing of 3-3-3-10-1 KHX11000D3LLV512 memory module has a timing of 7-7-7-7-20 It seems that the DDR3 memory module is faster than DDR, but its timing values ​​are worse. But this only seems to be so, since the frequency of DDR3 is higher, therefore, the timings were larger, although the main time delays for both types of microcircuits are approximately the same. Kingston DDR3 memory timings are listed below. Note that for other manufacturers the timings may be slightly different due to the specifics of the production of microcircuits and the layout of the memory module.

RAM timings can be adjusted in BIOS during system overclocking (it is not recommended to do this for inexperienced users).

Types of RAM

In order to fully uncover the question of what is the computer’s RAM – you must definitely touch on the varieties. There are currently two of them:

  • Statistical type of memory
    It is expensive and requires a lot of space, therefore it is used, as a rule, in specialized devices or for a small cache in microprocessors. This memory is called SRAM (Static random access memory), it’s based on semiconductor triggers and has a high speed.
  • Dynamic type of memory
    A more common type, which is made on the basis of capacitors, has a high recording density and is inexpensive. It is called dynamic because capacitors are quickly discharged and require periodic recharging of the charge. The official name is DRAM (Dynamic random access memory).
Ram type

Slots for installing RAM modules are located on the motherboard. Special cutouts are made on the memory bar that will not allow the plate to be inserted incorrectly. The modules installed on the PC must have the same parameters. Otherwise, the device will operate at the lowest technical specifications.

When mammoths still walked the earth, the RAM was divided into SIMM and DIMM – just forget about these types of RAM, they have not been released and used for a long time.
Then they invented DDR (2001) To date, four types of RAM have been released: DDR, DDR2, DDR3, DDR4. They are also divided into 2 forms of the factor: DIMM – for computers, SO-DIMM – for laptops. These two types are completely different, they cannot be confused, for computers they are elongated, for laptops they are short. Consider each generation of RAM separately.

The main difference between DDR2 and DDR3 is the number of contacts on the DDR memory board, there are only 184 of them. This type of RAM is much slower than its modern counterparts (DDR2 and DDR3).

  • DDR2 (2003), a larger number of contacts (240 pieces), due to this the number of data streams has expanded and the transfer of information to the processor has noticeably accelerated. The maximum frequency of DDR2 is 1200 MHz.
  • DDR3 (2007) – here they left the number of contacts alone (240 pieces) but made them electrically incompatible. The maximum frequency of DDR3 is 2400 MHz. This type of memory also has less power consumption and more bandwidth, DDR3 is 15-20% faster than DDR2.
  • DDR4 was announced in 2010, and the first bar was released a year later. This is the most common type of RAM in modern computers. This modern type of RAM consumes 35% less energy than DDR3 and in terms of bandwidth exceeds the previous generation memory by as much as 50%. The number of contacts in DDR4 increased to 288 pieces (located denser), and the frequency right up to 4200 MHz.

DDR is the first type of memory; it is over 20 years old. It uses a voltage of 2.6V. DDR SDRAM Specifications:

DDR2 – the second generation of RAM, first appeared in 2003. It uses 1.8V voltage. DDR2 Specifications:

DDR3 is the third generation, and it is divided into three types with different voltages: DDR3 – 1.5V, DDR3L – 1.35V, DDR3U – 1.25V. Release of all modifications from 2007 to 2010. DDR3 Specifications:

DDR4 is the last generation to date, entered mass production in 2014. The consumed voltage is 1.2V. It has a larger number of different timings. DDR4 Specifications:

In DDR4 Memory bandwidth has increased again, now reaching 25.6 Gb / s. The operating frequency also rose – on average from 2133 MHz to 3600 MHz. If we compare the DDR4 type with DDR3, which lasted on the market for 8 years and became widespread, then the performance gain is negligible.
Differences DDR4:
Incompatibility with previous types · Reduced supply voltage – from 1.2 to 1.05 V, power consumption also decreased · Operating memory frequency up to 3200 MHz (can reach 4166 MHz on some bars), while, of course, the timings increased proportionally · May slightly exceeds in speed work DDR3

As you probably noticed, each subsequent generation consumes less energy but produces higher performance. What gives efficiency in work and the minimum energy consumption.

RAM bar form factor

RAM slots for laptops (SODIMM) and desktop computers (SDRAM) are different in size and appearance. For laptops, they look like this …

SODIMM Laptop Ram

… and for desktop home computers, something like this …

ddr4 ram

This is where their differences (mostly)

Dual Channel Memory
I highly recommend using dual-channel when buying and installing memory. Simply put, if you decide to purchase 4 GB of RAM – buy two 2 GB strips. If 8 GB – two strips of 4 GB.

You also need to definitely set the brackets so that they work in dual-channel mode. Usually, the memory slots on the motherboard are painted in two colors …

So install your two RAM slots in the same color slots.

what is ram dual channel

Dual Channel is a technology that improves the transfer speed by installing two memories of the same standard and the same capacity on a PC.
Most modern computers are dual channel compatible.

The reason that the memory sold may be x2 or a pair is because the dual channel is considered.
For a dual-channel personal computer, for example, it is said that a 1GB x 2 memory is faster than a 2GB x 1 memory.

However, there is almost no speed difference that can be experienced.
The one used in pairs is called a triple channel. Triple channels are used on some computers.

Dual channel ram vs single channel

If you are building or upgrading your system, your system RAM must be one of the most important things in your mind. Most people believe that RAM speeds up the processor. But unlike public opinion, random access memory (RAM) basically prevents a system from performing at its best. This is because the processor is always faster than RAM and must wait for the processor to send data out of RAM. During this waiting time, the CPU is idle, wasting power and time.

Recent advances in technology have attempted to overcome the speed barrier by moving to dual, triple, or even quad channel technology to increase speed, but the most common is dual channel. But how much does it really bring? Today, we compare single-channel and dual-channel memory modules to see if the hype surrounding dual-channel is real. Is an upgrade worth it?

Computer ram Bandwidth of the communication channel theoretical of maximum transfer rate is, is measured in megabytes / second (MB / s) = one or gigabytes / sec (GB / s). Current technologies such as DDR (double data rate) are capable of transferring two data bits per clock cycle. As a result, it achieves twice the transfer rate compared to conventional memory technology. For example, a DDR3-1333 MHz module actually operates at 666.6 MHz, but transfers 2 data bits per clock cycle. In addition, the bandwidth also depends on the width of the data bus. A single channel uses a 64-bit device width. This basically means that 64-bit data is transferred in each transfer cycle. So, in theory, the bandwidth can be calculated as:
Bandwidth =DDR clock rate x data bus width/8

Thus, for a single-channel DDR3-1333 memory, the theoretical bandwidth is:
Single channel bandwidth =1333 x 64/8 = 10,664MB/s or 10.6GB/s

Newer technologies, such as dual channel technology , focus on doubling the data bus width by increasing the number of data wires available on the memory bus . Dual channel uses a device width of 128 bits. This means that 128 bits of data are transferred in each transfer cycle (see architectural differences above). This theoretically affects the system by doubling the bandwidth. For example, for a dual-channel DDR3-1333 memory, the theoretical theoretical bandwidth is:
Dual channel bandwidth = 1333 x (64 x 2) / 8 = 21,328 MB / s or 21.3 GB / s

Note : The difference in bandwidth is amazing, but keep in mind that this is just a theoretical calculation of the two values. Actual performance of single-channel and dual-channel memory may vary.

Single channel or dual channel memory: which is better?
In summary, I do, however, when comparing single-channel and dual-channel memory, dual-channel comes out as the winner
Single Channel vs Dual Channel Memory: What’s Good for You?
A dual-channel memory performs better than single-channel memory modules, but the difference is not surprising. After all, it all comes at a price. There may be cases where a dual memory kit can be purchased cheaper than a single memory module, or vice versa. That being said, purchasing a single-channel memory leaves the door open for future dual-channel utilization. The only thing you need to remember is the fact that it should be similar, if not identical, to a pre-existing memory to ensure that your future purchases work properly.

Benefits of increasing ram memory

Memory is like a workbench in the real world.
If the workbench is small, things will be scattered and it will be difficult to take out the necessary things, which will reduce the processing efficiency.
On the other hand, a large workbench facilitates work and improves work efficiency.

On a personal computer, expanding the work surface is done by increasing the memory.
The additional memory increases the efficiency of reading and writing data, which increases the speed of your computer.

If your PC freezes or it takes a long time to open a file, you may need to check the amount of memory once, as adding more memory may solve the problem.

For light tasks such as e-mail and word processing, you can use the standard RAM of about 4GB without any problem. However, for advanced tasks such as video and images, it is safe to have 8GB or more.

However, it is not always possible to increase the memory on your PC.
With a 64-bit OS, you can add more than 8GB, but with a 32-bit OS, only 4GB is recognized (for 32-bit Windows, about 3GB is recognized), so work efficiency may not be improved due to additional memory.

What ram frequency to choose?

Choosing a frequency you need to start by checking the maximum supported frequencies with your processor and motherboard. It makes sense to take a frequency higher than that supported by the processor only when overclocking the processor.

Today, you should not choose a memory with a frequency below 1600 MHz. The 1333 MHz option is valid in the case of DDR3, if it is not ancient modules that were lying around at the seller, which will obviously be slower than the new ones.

The best option for today is a memory with a frequency interval from 1600 to 2400 MHz . The frequency above has almost no advantage, but it costs much more, and as a rule it is overclocked modules with raised timings. For example, the difference between the modules in 1600 and 2133 MHz in a number of working programs will be no more than 5-8%, in games the difference can be even less. Frequencies in the 2133-2400 MHz are worth taking if you are engaged in video/audio encoding, rendering.

The difference between the frequencies of 2400 and 3600 MHz will cost you quite expensive, while not adding significantly to the speed.

How much RAM do i need?

The volume that you need depends on the type of work performed on the computer, the installed operating system, and the programs used. Also, do not lose sight of the maximum supported memory capacity of your motherboard.

how much ram do i need
  • The volume of 2 GB – for today, maybe enough only to browse the Internet. The operating system will eat more than half, the remaining will be enough for unhurried work of undemanding programs.
  • The volume of 4 GB is suitable for a computer of the middle hand, for a home PC media center. Enough to watch movies, and even play undemanding games. Modern – alas, it will be difficult to pull. (It will be a better choice if you have a 32-bit Windows operating system that sees no more than 3 GB of RAM)
  • The volume of 8 GB (or a set of 2x4GB ) is the recommended amount for today for a full-fledged PC. This is enough for almost any game, for working with any resource-demanding software. The best choice for a universal computer.
  • The volume of 16 GB (or sets of 2x8GB , 4x4GB ) – will be justified if you work with graphics, heavy programming environments, or constantly render video. It is also perfect for online streaming – there may be freezes with 8 GB, especially with high quality video streaming. Some games in high resolutions and with HD textures can behave better with 16 GB of RAM on board.
  • The volume of 32 GB (a set of 2x16GB , or 4x8GB ) is still a very controversial choice, useful for some very extreme work tasks. It would be better to spend money on other computer components; this will have a stronger effect on its speed.

Do I need Ram heatsink?

Now is not the time when the operating frequency of 1600 MHz was reached at a voltage of 2 V, and as a result, a lot of heat was released, which had to be somehow removed. Then the radiator could be a criterion for the survival of the overclocked module.

memory heatsink

Currently, the memory power consumption has decreased significantly, and the heatsink on the module can be justified from a technical point of view only if you are into overclocking and the module will work at frequencies beyond its limits. In all other cases, radiators can be justified, perhaps, with a beautiful design.

ram heatsink

If the heatsink is massive, and significantly increases the height of the memory bar – this is a significant minus, since it can prevent you from putting a processor super cooler into the system. By the way, there are special low-profile memory modules designed for installation in compact cases. They are slightly more expensive than regular size modules.

Difference between Computer RAM and ROM

The role of RAM is “memory”. Therefore, since it becomes a temporary work area, the data in the RAM is frequently rewritten, and when the power is turned off, the temporary data used for work is also erased.

On the other hand, in the case of ROM (rom), as the name “Read Only”, it refers to memory that is not writable and can only be read.
In the past, NES and Super NES cassettes were also called “Rom cassettes”.

Therefore, the role is “storage”. So you’re assuming an operation method that won’t be added once you write it.

ROM is easy to compare and confuse with RAM because it has a suffix at the end, but in such a case it may be easier to recall the NES cassette and get an image.
PCs and smartphones require RAM and memory to temporarily store processed data, etc., in addition to the CPU that actually performs the calculations.
If the amount of RAM in the PC is small, the operation of the PC will be hardened or slowed down.
To speed up the operation, it is effective to add memory.
However, depending on the type of Windows, memory expansion may not be possible.
First, check the amount of RAM and the type of Windows, and consider adding more memory.

DRAM development

In the past few years, the main battle for increasing computer performance has been in the development and manufacture of new high-speed memory chips. Moreover, if before all the improvement of RAM was reduced to increasing its volume, now acceleration of the process of reading / writing memory cells and data transfer via the system bus is paramount. Thus, the developers finally came to the conclusion that it is pointless to increase the frequency of the processor core without speeding up the process of working with RAM, because the processor, having processed the data portion received before it, stops for a long time, waiting for the end of the next read / write cycle . Improving the memory chips, of course, entails a change in the design of the chipset of the motherboard and the rules of operation of the system bus. As a result, users now face not only the problem of choosing a new processor and motherboard, but also the selection of the best option for a processor-board-memory system. Indeed, today there are three types of modules (DDR, DDR2, DDR3 ) for working with modern processors, and the choice between DDR2 and DDR3 modules is not so obvious. In addition, to control a certain type of memory, it is necessary that the chipset of the system board or the processor memory control unit is able to work with it.

Before Pentium III processors appeared, users had no particular choice of memory modules, but the main problem in practice was how to distinguish between SIMM (Single In-line Memory Module) and EDO (Extended Data Output) and FPM (Fast Page Mode) chips . New generations of processors stimulated the development of faster SDRAM (Synchronous Dynamic Random Access Memory) with a clock frequency of 66 MHz, and memory modules with such chips were called DIMM (Dual In-line Memory Module). Currently, the process of abandoning the use of DDR memory modules in favor of DDR2 has almost ended, and the transition to the next generation of DDR3 memory modules has also begun. For Intel processors, this transition to DDR2 and 3 practically took place, and for AMD processors started after the release of sockets АМ2 and 3. Regarding the DDR3 memory, it should be noted that the serial production of the modules started only in 2007, therefore this memory is still expensive, and in most cases it is still not needed, since most systems and DDR2 memory is quite enough. In general, this is still a question of how much the latest memory is needed, since in real life and for most applications, the results of practical work do not coincide with overly optimistic measurements in various tests.
In addition to these types of memory, there are other types of memory and modules that are used in specialized devices, for example, as video memory. It should be noted that there are constantly reports about the development of memory chips based on new principles, ‘therefore, perhaps in a year or two DDR SDRAM chips will be considered obsolete.

DIMM Design

64-bit memory modules DIMM (Dual In-line Memory Module) appeared in 1997. This generation of memory modules has 168 contacts located on both sides of the PCB (84 contacts on each side).

DIMM Design

To identify the type of module of the DIMM form factor by the amount of memory and the type of microcircuit used, a flash memory microcircuit is installed on the module with service information recorded in it (SPD — Serial Presence Detect), accessed via the 1 ~ C interface. In order to prevent the improper type of DIMM module being installed, several slots (keys) are made in the PCB of the module among the contact pads, as well as on the right and left in the zone of module fixing elements on the system board. For the mechanical identification of various DIMM modules, a shift of the position of two keys in the module’s PCB located among the contact pads is used. The main purpose of these keys is to prevent a DIMM module with the wrong voltage supply from the memory chips from being installed in the connector. Moreover,

DIMM module

Various modifications of Pentium 4 and Celeron processors, as well as Athlon and Semptron are designed to work with such modules. The corresponding keys are used to identify the supply voltage of the DDR SDRAM modules. On modules of type Registered DIMM (with data buffering), one or two chips for temporary data storage are installed between contacts and DRAM microcircuits. In low-profile modules, buffering chips are installed in the middle of the module (or under the main chips). Since high-speed memory chips, like processors, generate a lot of heat, the most advanced modules are equipped with radiators.


In some severe cases, it is necessary to use forced cooling of the modules, in particular, if the memory is overclocked. In DDR2 SDRAM modules, the number of contacts is increased to 240

SDRAM modules

The corresponding keys are used to identify the DDR2 SDRAM modules. In DDR3 SDRAM modules, the number of contacts is left 240, like in DDR2 modules, but the key position is changed. DDR2 and DDR3 modules are incompatible in pin assignment and supply voltage. The key for DDR3 modules is shifted relative to the DDR2 key by about a dozen pads.

Attention! Do not increase the voltage of the DDR3 memory modules when working with the Intel Core i7 processor above 1.65 V, as this may damage the processor input circuits.

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