What does low profile RAM mean. Glossary of terms: RAM

RAM- one of the most important components of the system, on which the performance of the computer directly depends. In the catalog, you can choose and buy RAM of a suitable type with a capacity from 1 to 32 GB, single sticks, as well as KIT memory modules of 2 and 4 sticks complete with the same characteristics, selected for pairing (dual-channel mode). The use of dual-channel mode leads to a significant increase in throughput, and, consequently, to an increase in the speed of applications. For compact systems, low-profile memory modules are provided that differ from standard ones in height, but not in performance. While for legacy platforms, regular and server RAM modules of the Registered DDR, DDR2, Registered DDR2 and DDR2 FB-DIMM standards are presented. Affordable prices These standards make the choice an obvious choice when looking for a replacement for a failed memory or expanding the available total memory in a system.

Today, the most common type of memory for Intel and AMD based desktop PCs is DDR3 RAM. However, undervoltage (LV DDR3) is not supported by all motherboards and processors.

For the most modern processors fits . It features doubled to 3.2 Gbps maximum speed data transmission, increased to 4266 MHz maximum frequency and unsurpassed stability. The increased pin count makes DDR4 modules incompatible with older slots.

The higher the clock frequency, the more operations are performed per unit of time, which allows computer games and other applications to work more stably and quickly. Prices for high-clocked RAM are, needless to say, higher. But before you buy memory, pay attention to what maximum frequency is indicated in the description of the processor. Using memory with frequencies higher than the declared values ​​will not give a noticeable performance boost.

If you are building a gaming computer, a powerful workstation or plan to overclock all system components, then you should buy game memory that is different from the standard increased frequency, increased voltage and, if possible, lower delays. The prices for gaming memory are not the lowest, but in this case, the system performance will be higher than when using standard memory sticks. The decoration of any gaming PC will be backlit. White or multi-color backlighting does not affect performance, but it looks very stylish and relevant for a PC of this class.

Fast memory modules are distinguished by the presence of profiles that expand the capabilities of SPD. To the most popular this moment applies so-called . XMP support allows you to overclock DDR3 and DDR4 memory to achieve even better performance and better gaming features without complex memory voltage and clock changes.

This is a module whose function is to store data and provide it on demand to a device or program - in fact, it is an intermediary between the processor and disk drives. RAM is a volatile device, i.e. can only work while it is powered, when it is turned off, all data is lost. Let's take a closer look at the characteristics of this essential device, without which your PC, smartphone, laptop or tablet will be an ordinary pile of iron.

RAM types

There are several types of RAM, radically different in characteristics and architecture.

– synchronous dynamic random access memory. It used to be quite popular and was used in almost all computers, due to the presence of synchronization with the system generator, which, in turn, allowed the controller to very accurately determine the time when the data would be ready. As a result, the delay time for waiting cycles was significantly reduced due to the availability of data at each timer cycle. Today is supplanted by more modern types memory.

is a dynamic synchronized memory, it is based on the principle of random access and double data exchange rate. Such a module has a number of positive characteristics relative to SDRAM, the most important of which is that 2 operations are performed per 1 cycle of the system generator, that is, at a constant frequency, the bandwidth at the peak increases by 2 times.

- this is the next development, it works in the same way as for DDR type RAM, a distinctive feature of this model is a doubled data sampling per cycle (4 bits instead of 2x). In addition, the second generation has become more energy efficient, heat dissipation has decreased, and frequencies have increased.

- a new generation of RAM, the most important distinguishing feature from DDR2 is increased frequencies and reduced power consumption. The design of the keys has also been completely changed (special slots for precise entry into the slot).

There are modifications of DDR3 that differ in even lower power consumption - DDR3L and LPDDR3 (the voltage for the first model is reduced to 1.35 V, and for the second to 1.2 V, while for simple DDR3 it is 1.5 V).

DDR4 SDRAM - newest generation random access memory. It is characterized by a data exchange rate increased to 3.2 Gb / s, a frequency increased to 4266 MHz and significantly improved stability.

RIMM(RDRAM, Rambus DRAM) is a memory based on the same principles as DDR, but with an increased clock frequency, which was achieved due to a smaller bus width. Also, when addressing a cell, the row and column numbers are transmitted simultaneously.

The cost of RIMM was much higher, and the performance was only slightly higher than DDR, as a result, this type of RAM did not last long on the market.

Choose the type of RAM not only based on the potential and characteristics of your motherboard, but also taking into account compatibility with other components of the system.

Options for the physical location of the chips (packaging)

Memory chips installed on RAM modules are located either on one side (single-sided location) or on both sides (double-sided). In the latter version, the modules are thick enough that they cannot be installed on separate PCs.

Form factor is

A specially developed standard that describes the dimensions of the RAM module, the total number and location of contacts. There are several types of form factors:

SIMM (Single in Line Memory Module) - 30 or 72 double-sided contacts;

RIMM- proprietary form factor of RIMM modules (RDRAM). 184, 168 or 242 contacts;

DIMM(Dual in Line Memory Module) - 168, 184, 200 or 240 independent pads located on both sides of the module.

FB-DIMM(Fully Buffered DIMM) - exclusively server modules. Identical in form factor to 240-pin DIMMs, but use only 96, due to the serial interface. Thanks to the AMB (Advanced Memory Buffer) chip present on each module, high-speed buffering and conversion of all signals, including addressing, is ensured. Performance and scalability have also been greatly improved. Compatible only with similar fully buffered memory.

LRDIMM(Load Reduced Dual In-Line Memory Modules) - exclusively server modules. Equipped with an iMB buffer (Isolation Memory Buffer), which reduces the load on the memory bus. They are used to speed up the work of large amounts of memory.

SODIMM(Small Outline Dual In-Line Memory Module) - a subspecies of DIMM with smaller dimensions for installation in portable devices mostly laptops. 144 and 200 contacts, in a rarer version - 72 and 168.

MicroDIMM(Micro Dual In-Line Memory Module) - an even smaller SODIMM. Usually have 60 contacts. Possible pin implementations are 144 SDRAM, 172 DDR and 214 DDR2.

Special mention deserves low-profile (Low Profile) memory - modules designed specifically for low-rise server cases with a lower height compared to standard ones.

Form factor is the main parameter of RAM compatibility with motherboard, since if it does not match, the memory module simply cannot be inserted into the slot.

What is SPD?

Each DIMM form factor has a small SPD (Serial Presence Detect) chip that stores data about the parameters of physical chips. This information is critical to business continuity and is read by the BIOS during the test phase to optimize RAM access settings.

Ranks of the memory module and their number

A 64-bit wide memory block (72 for ECC modules) formed by N physical chips. Each module can have from 1 to 4 ranks, and motherboards also have their own limit on the number of ranks. Let us explain - if no more than 8 ranks can be installed on the motherboard, then this means that the total number of ranks of RAM modules cannot exceed 8, for example, in this case - 8 single-rank or 4 dual-rank. Regardless of whether there are still free slots - with the exhausted limit of ranks additional modules will be impossible to install.

Determining the rank for a particular RAM is quite simple. At Kingston, the number of ranks is determined by one of 3 letters in the center of the marking list: S is one-rank, D is two-rank, Q is four-rank. For example:

• KVR1333D3L S 4R9S/4GEC
• KVR1333D3L D 4R9S/8GEC
• KVR1333D3L Q 8R9S/8GEC

Other manufacturers indicate this parameter as, for example, 2Rx8, which means:

2R - two-rank module

x8 - data bus width on each chip

those. 2Rx8 module without ECC has 16 physical chips (64x2/8).

Timings and latency

The execution of any operation by the memory chip occurs in a certain number of system bus cycles. The number of cycles required for writing and reading data are the timings.

Latency, in short - the delay in accessing memory pages, is also measured in the number of cycles and is written in 3 numerical parameters: CAS Latency, RAS to CAS Delay, RAS Precharge Time. Sometimes a fourth digit is added - "DRAM Cycle Time Tras / Trc", which characterizes the overall performance of the entire memory chip.

CAS Latency or CAS(CL) - waiting from the moment when the data was requested by the processor and before it is read from RAM. One of the most important characteristics that determine the speed of RAM. A small CL indicates high RAM performance.

RAS to CAS Delay(tRCD) - the delay between the transmission of the RAS (Row Address Strobe) signal and the CAS (Column Address Strobe) signal, necessary for a clear separation of these signals by the memory controller. Simply put, a data read request includes row and column numbers of a memory page, and these signals must be distinct, otherwise multiple data errors will occur.

RAS Precharge Time(tRP) - defines the delay time between deactivation current line data and activation of a new one. In other words, the interval after which the controller can again send RAS and CAS signals.

Clock frequency, data rate (Data rate)

Data transfer rate (otherwise - data transfer rate) - the maximum possible number of data transfer cycles per second. Measured in gigatransfers (GT/s) or megatransfers (MT/s).

The clock frequency determines the maximum frequency of the system oscillator. It must be remembered that DDR stands for Double Data Rate, which means twice the data exchange rate relative to the clock. So, for example, for the DDD2-800 module, the clock frequency will be 400.

Bandwidth (peak data rate)

In a simplified version, it is calculated as the frequency of the system bus multiplied by the amount of data transmitted per clock.

The peak speed is the product of the frequency and bit width of the bus and the number of memory channels (H×R×K). The memory module is marked as, for example, PC3200, which obviously means that the peak data transfer rate for this module is 3200 MB / s.

For optimal performance system, the total value of the memory strips SRPD should not exceed the processor bus bandwidth, with the exception of the dual-channel mode, when the strips occupy the bus one by one.

What is ECC (Error Correct Code) support

Memory with ECC support allows you to find and correct spontaneous errors during data transfer. Physically, ECC is implemented as an additional 8-bit memory chip for every 8 main ones and is a much improved "parity check". The essence of this technology is to track one bit arbitrarily changed in the process of writing/reading a 64-bit machine word with its subsequent correction.

Buffered (registered) memory

It is characterized by the presence of special registers (buffers) on the RAM module that process control and addressing signals from the controller. Despite the additional delay cycle due to the buffer, registered memory is still widely used in professional systems due to the reduced load on the synchronization system and significantly increased reliability.

It must be remembered that buffered and unbuffered memory are incompatible and cannot work in the same device.

The type of RAM that determines the main characteristics of the memory and the internal structure. Today, five main types of RAM are produced: SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RIMM.
SDRAM is a synchronous dynamic memory with random access. Advantages compared to older generations of memory: synchronization with the system clock, this allows the memory controller to know the specific data readiness time, with this innovation, time delays during wait cycles are reduced due to the fact that data is free to be available during each clock cycle timer. Previously, SDRAM was actively used in computers, but now DDR and DDR2 are almost completely supplanted.
DDR SDRAM is a synchronous dynamic memory with random access and is characterized by a double data transfer rate. Advantages of DDR SDRAM over SDRAM: in one cycle of the system generator, it is possible to carry out two operations with information, which doubles the peak throughput when operating at the same frequency.
DDR2 SDRAM is the next generation of memory after DDR. The principle of operation is similar to that used in DDR. Difference: it is possible to sample 4 bits of data per cycle (2-bit sampling is performed for DDR), the operating frequency is increased, the power consumption of memory modules is reduced, and heat dissipation is reduced.
DDR3 SDRAM is the next generation of DDR2 SDRAM memory, using the same "frequency doubling" technology. The main difference from DDR2: the ability to work at a higher frequency. DDR3 modules have 240 pads available, but they are not compatible with older slots because different orientation slots ("keys") are used.
RIMM (Rambus DRAM, RDRAM) is a synchronous dynamic memory developed by Rambus. The main differences from DDR memory are: an increase in the clock frequency by reducing the bus width, simultaneous transmission of the column and row numbers of the cell when accessing the memory. RDRAM is much more expensive than DDR, and with similar performance, this has led to the fact that given type memory almost completely left the market.
When deciding on the type of memory, focus primarily on the capabilities of your computer's motherboard, as well as its compatibility with different memory modules.

Form Factor
RAM module standard. The form factor (standard) determines the dimensions of the memory module, as well as the number of pins and their location. There are several completely incompatible memory standards: SIMM, DIMM, FB-DIMM, SODIMM, MicroDIMM, RIMM.
SIMM - memory modules of this standard often have 72 or 30 pins, each of these pins is equipped with an output on two sides of the memory board.
DIMM - memory modules of the DIMM standard, they usually have 240, 200, 184 or 168 independent pads, the pads are located on two sides of the memory board.
DDR2 FB-DIMM - memory modules of this standard are used in servers. They are mechanically similar to 240-pin DIMMs, but are completely incompatible with conventional unbuffered Registered DDR2 DIMMs and DDR2 DIMMs.
SODIMM is a compact version of DIMM commonly found in Tablet PCs and laptops. Most often it has 72, 144, 168, 200 contacts.
MicroDIMM is one of the DIMM options for subnotebooks and laptops. Dimensions are smaller than SODIMM, characterized by the presence of 60 pads.
RIMM is a standard for RIMM type memory modules (RDRAM), characterized by the presence of 184, 168 or 242 pins.
The standard of the RAM module and the standard that the motherboard supports must match.

The volume of one module
from 0.03125 to 128 GB
The amount of memory that one module has. The total system memory can be calculated by adding the memory sizes of all installed modules. For comfortable work in office programs and the Internet network is enough 512 MB. For normal work with office applications, as well as with graphic editors enough 1 GB (1024 MB) of RAM. Work in difficult graphic programs and play computer games will allow 2 GB (2048 MB) of system memory.

Number of modules
from 1 to 16
The number of memory modules sold in the set. There are not only single strips on sale, but also kits, there can be two modules in the kit, four, six, eight, they all have identical characteristics and are selected to work in two-channel mode (in pairs). The use of such a dual-channel mode allows you to achieve a significant increase in throughput, and, as a result, an increase in the speed of applications. It must be said that the fact that you bought two modules from the same manufacturer with the same characteristics does not mean at all that they will be able to work in dual-channel mode. For this reason, if your computer motherboard is capable of supporting dual-channel memory operation, then you should pay attention to kits consisting of several modules, if, of course, it is important to you high speed work of graphic and gaming applications.

Number of contacts
from 144 to 288
The number of contact pads located on the memory module. The number of pins on the module must match the number of pins in the RAM slot located on the motherboard. It must be remembered that in addition to the same number of contacts, the "keys" must also match ("keys" are called cutouts on the module, they exclude the possibility of incorrect installation).

Number of ranks
1 to 8
The number of memory areas (ranks) of the RAM module. A rank is a memory area that is formed by several chips or all chips of a memory module and has a width of 64 bits. The RAM module, depending on the design, may have one, two or four ranks. Server motherboards produced today are characterized by a limit on the total number of memory ranks, for example, if a maximum of eight ranks can be installed and four dual-rank modules are already installed, then it will no longer be possible to install additional modules in free slots, because. setting them will cause the limit to be exceeded. This is why single-rank modules are more expensive than two- and four-rank modules.

Clock frequency
66 to 4800 MHz
The lowest frequency of the system generator, it is used to synchronize the processes of receiving and transmitting information. For DDR, DDR2 and DDR3 memory, the clock frequency is doubled (two data operations are performed in one clock cycle). The higher the clock frequency, the large quantity operations per unit of time can be performed, this allows computer games and other applications to run more stable and faster. With all other identical characteristics, memory with a higher frequency is more expensive.

Bandwidth
from 1600 to 38400 Mb/s
The bandwidth of a memory module is the amount of information received or transmitted in one second. This parameter is directly dependent on the memory clock frequency. The bandwidth of a memory module is calculated by multiplying the bus width by the clock speed. The greater the bandwidth, the greater the speed of the memory, the greater the price of the module (if other characteristics are the same).

ECC Support
Support for the ECC (Error Checking and Correction) algorithm, which makes it possible to both detect and correct errors that accidentally occurred during data transmission (no more than one bit per byte). Error Checking and Correction technology is supported by almost all server boards, as well as some motherboards for workstations. Memory modules with ECC are more expensive than those that do not support this algorithm.

Buffered (Registered)
The presence of a buffer (special registers) on the memory module, special registers can quickly store incoming data, reduce the load on the synchronization system, thereby freeing the memory controller. The presence of special registers between the memory chips and the controller leads to an additional delay equal to one clock cycle when performing operations, thus higher reliability comes from a slight decrease in performance. Memory modules equipped with registers are characterized by high cost, they are mainly used in servers. It should be remembered that unbuffered and buffered memory are incompatible, which means that they cannot be used simultaneously on the same system.

Low Profile
A memory module that has a smaller height (compared to standard size). This size makes it possible to install it in low server cases.

Radiator
The presence of special metal plates fixed on the memory chips, these plates are designed to improve heat transfer. Heatsinks are usually installed on memory modules that are used to operate at high frequencies.

XMP support
XMP (eXtreme Memory Profiles) - a profile containing information about the extended and non-standard capabilities of the RAM module. Affordable Computer BIOS at the initial loading period, switching to the overclocking mode is carried out, without configuring all the delays manually.

Timings

from 2 to 22
CAS Latency, CAS - the number of cycles from the time of requesting data to reading them from the memory module. CAS Latency, CAS is the most important characteristic memory module, it will determine the speed of the memory. With a decrease in the number of CLs, memory operation is accelerated.

tRCD
from 2 to 26
RAS to CAS Delay is the delay between the signals that determine the column address and the row address.

tRP
from 2 to 26
Row Precharge Delay. This parameter determines the period of charge accumulation, the recharging of the RAS signal (reissue time), i.e. the time after which the memory controller can again issue a line address initialization signal.

tRAS
from 5 to 52
Activate to Precharge Delay is the smallest number of cycles between RAS (activation command) and Precharge (recharge command) or closing of the same memory bank.

Additional Information

Supply voltage
1.2 to 3.3 V
The voltage required to power the RAM module. All modules are designed for some specific voltage, so when choosing this item, make sure that your motherboard supports the required voltage.

chips

Manufacturer
The manufacturer of the microcircuits installed on the module. Often, memory module manufacturers use third-party chips to manufacture their products.

Quantity
from 1 to 184
The number of chips installed on one memory module. Chips can be located on either side and on both sides of the board.

Package
Method of arrangement of chips on the memory module. Modules are available with one-sided and two-sided packaging. If the chips on the module are located on both sides, then the modules are thicker, which prevents their installation in some systems.

Hello, dear readers of the blog site. Today I would like to talk about computer RAM. It (memory) is often called RAM - Random Access Memory, or RAM - which in bourgeois means "random access memory", that is, memory not only for reading, but also for writing information.

A little higher, I mentioned the word "device", although in reality RAM is not called a full-fledged device. In fact, RAM is one or, most often, several rectangular strips. Many, having come to a computer store, are perplexed how they can give 1000-2000 rubles for some garbage! (depending on the amount and type of memory of course). And the bar is 2000 rubles. far from the limit, believe me, there are even more expensive ones - 5-6 times so.

The fact is that the computer's RAM is needed to store temporary information, i.e. until the computer is turned off. Time information means OS ( operating system), All open programs and services and even little things all garbage. It turns out that the larger the amount of RAM, the more programs you can open at the same time, the faster the OS itself will work, since there will be no need to constantly load OS files from . There are of course many advantages, but the main ones are still - speed and multitasking. In the situation with games, there is nothing to talk about at all, everything is simple here, the more the better. But, I think 16 GB for games will still be a bit much.

In 2006-2007, having even 1 GB of RAM "on board" was very cool. And although this volume was enough for most everyday tasks, it felt like the system was slowing down, and in games this was more noticeable. In fact, volume is not the only important characteristic of RAM, there are two more: the type of memory and its frequency. I propose to talk about this in more detail.

But first, let's take a look where is RAM located.

As you can see, the RAM strips are attached to using special connectors, these connectors (slots) are only suitable for connecting computer RAM, no other devices can be connected there, as is the case with (where the PCI-E x16 slot serves as the connection interface, to which other devices can be connected besides the video card).

As you understand, not all RAMs are alike. I propose to see how they can differ from each other. The first difference can be seen simply by looking at memory. I'm talking about the height of the memory bar itself. Yes, quite recently, a "low-profile" version of it has been added to the already familiar conventional memory, look here:

This type of memory will be convenient for installation, especially if the space in system block very limited, although initially this species memory was used for installation in server cases, due to the horizontal location and low height of the latter.

So, as mentioned above, volume is not the most important parameter that characterizes the computer's RAM. What if the computer has a 4 GB RAM bar, but the type of this memory is outdated, or the operating frequency is low.

What is this type of such, you may ask? I answer there are two types of RAM, which differ from each other in the actual design of the bar itself and the speed of its operation (performance). Both of these types of memory are called DDR2 and DDR3, respectively.

At the time of this writing, DDR2 has almost been squeezed out of the market by its descendant - DDR3, due to the fact that the power consumption of DDR3 memory has decreased by various estimates by 15% compared to DDR2. And DDR3 has much more throughput and stably operates at a frequency up to 1600 MHz. Please note that these two types of memory are not compatible with each other, and all because there are differences even in the memory connectors themselves.

The images above clearly show the reason for the incompatibility, namely, a small recess in the RAM sticks, as well as a small notch in the memory slots on the motherboard. All this will not allow you to accidentally put one type of memory into a computer instead of another, such is "protection for a fool." By the way, everything that was stated above in the text does not describe all the differences between DDR2 and DDR3 memory, but that was not the purpose of this post. I can only say that there will be other articles related to the topic "computer RAM". Perhaps this is all I would like to talk about here. See you!

ATTENTION! This article is not a call to action, but is for informational purposes only.

It is an equally important part of the computer. Despite the fact that this part is small, the speed of your computer largely depends on it. It has basic characteristics such as volume and frequency.

RAM

The essence of the action of RAM can be understood from its name: this is the memory that should work quickly. For example, you have HDD on which some data is stored. You run an application that receives data from hard drive needed for work. If the computer constantly accesses the hard disk for the data it needs, then it will take quite a lot of time - therefore, it loads this data into RAM and can access it much faster, “here and now”. It follows that the more RAM, the better.

As in the case of other computer components, the amount of RAM should be chosen based on goals. If you work only with undemanding office applications, then a large amount of RAM will simply be idle, and this is an extra overpayment of money, while at the same time, users who work in more serious programs, for example, gamers, need more RAM. Nevertheless, you should stick to the optimal option and purchase at least four gigabytes of memory - this amount will be quite enough for comfortable work. home computer, even for entertainment in games.

RAM frequency

Such a concept as the frequency in RAM is responsible for its speed. That is, with what speed the computer will be able to take and load the necessary data into this very memory. The principle “the more the better” also applies here.

There are several types of RAM. These are DDR, DDR2 and DDR3. Each of them differs in that it has a maximum frequency greater than that of the previous type. The best option would be a frequency from 1200 to 1600 MHz. If the budget is limited, then you should give preference to RAM with a lower frequency, but not less than 1200 MHz. This is due to the fact that the price of such memory will be less, and performance differences ordinary user won't even notice.

Important points to pay attention to

The most important thing is that the parts in our computer are not only fast, but also fully compatible. Therefore, you should definitely make sure that the type of memory, its volume and frequency match the same parameters on the motherboard. If these parameters are incompatible, then it will either not work at all, or it will not work the way we would like. For example, if the maximum allowable amount of RAM on the motherboard is 8 gigabytes, and a “bar” of 16 gigabytes of RAM is inserted, only half of the memory will be used, that is, extra money was overpaid.

So, there are regular and low-profile "bars". Low profile have smaller sizes, which are suitable for small cases, but inserting a “bar” of a regular size into such a case will already be difficult. In order not to be mistaken, in any case, you can take low-profile "bars", since they are suitable for any case, and their performance does not differ. Otherwise, be sure to make sure that the dimensions of the "bars" of RAM fit your case and motherboard.