How to choose RAM?

Replacing the RAM - decent tuning of the good old PC. With RAM, you can increase the speed, performance and memory of your computer. But you need to replace the device wisely: you can not just buy RAM. It should correspond to the processor and the motherboard of the computer. Therefore, in the question of what RAM to choose, experts recommend to refer to the characteristics of these particular components.

In order to determine which processor supports the motherboard, and what memory it needs, you should:

  • Look at the site of the manufacturer of the board.
  • Find your model there by alphanumeric marking.
  • Investigate a guide to supported processors and a list of those memory modules that manufacturers recommend for them.

So, what are the most important criteria when choosing RAM?

Memory type

Despite the fact that the IT-technology market is rapidly improving, each time throwing much more interesting models to consumers, we will tell you about the main dominant types of memory today:

  • 3rd generation DDR memory module or DDR3 (2400 megahertz clock speeds). Energy consumption and heat dissipation of this model is reduced by 40%.
  • DDR2 memory module.
  • DDR1 memory module.

All these modules are completely incompatible with each other both in electrical and physical parameters. For this reason, even with an error of choice, you will not be able to insert into the PC that bar that does not fit.

Form factor

A form factor is a standard that specifies the dimensions of a device or, more simply, the type of construction of the plank. There are two of them:

  • DIMM. Used for desktops and assumes contacts are on both sides
  • SO-DIMM. Used for laptops

Visually, their sizes differ almost twice (SO-DIMM is smaller).

Bus frequency and data transfer rate (bandwidth)

These parameters are considered basic. They characterize the performance of the "RAM" and give as a result the answer, how to choose the RAM.

  • The bus frequency shows its ability to transfer data in one unit of time. The higher this indicator, the more information can be “merged”.
  • Memory bandwidth determines the frequency that transmits data, the bus discharge and the number of memory channels.

Both parameters are directly proportional. For example, if the bus frequency of the memory is 1333 MHz, then its capacity will be 10,600 MB / s, and the following message will appear on the RAM: DDR3 1333 PC-10600.

How to choose the RAM, focusing on the frequency of the bus:

First and foremost, build on the capabilities of the system. Ideally, the bus frequency coincides with the frequency of the motherboard / processor. For example, if you purchased a DDR3-1800 module, and the connector supports a maximum of DDR3-1600, the RAM will work only at the frequency of the connector - 1600 MHz. Moreover, in this situation, malfunctions of the entire system are possible. So, to solve this problem, it is better to get the DDR3-1600 or DDR3-1333 RAM.

Memory Modes

In modern PCs, RAM modes of operation support motherboards. It is in these modes, the speed of work will be most effective. So for maximum computer speed, consider both the modes of operation of the modules and their correct installation.

There are several types of memory modes:

  • Single channel (asymmetric). It is turned on when a single RAM module is installed in the PC, or in the case when all the modules are different in terms of memory size, by manufacturer or frequency of operation. It does not matter the memory itself, and in which connector it is installed.All RAM will start operating at the slowest speed available on the PC.
  • Dual channel (symmetrical). In the two channels are installed modules with the same amount of "RAM". Thus, the maximum data transfer rate is actually doubled. It is most common in practice.
  • Three channel. It assumes that the same amount of memory is installed in each of the three available channels. All modules are sorted by speed and volume.
    But professionals point out that such a mode is often less productive than dual channel mode.
  • Flexible mode. It gives you the opportunity to increase the performance of the RAM if two modules of different volume are installed, but of the same frequency.

Memory size or size

It is believed that the amount of memory is almost the main characteristic of the module. It is assumed that the more it is, the better for the PC. But this is not always the case, although it is encountered in practice.

Experts also claim that the volume of 6 GB is quite reasonable, especially in cases where the disk subsystem is weak.


Or temporary delay, the latency of the RAM. Specified as a sequence of several numbers, for example, 3-3-3.They denote the following parameters:

  • cycle time (CAS Latency);
  • full access time (RAS to CAS Delay);
  • RAS Precharge Time.

The lower the timings, the faster the RAM. They are measured in nanoseconds (ns) and take values ​​from 2 to 9.

Sometimes in the characteristics given a single digit. It means the first parameter is the duty cycle time. In this case, the rest will be either equal to him or more. So do not trust the marketing move.

When choosing a memory should be guided by the lowest timings. If it is a question of adding an additional module to the PC, then the CL of the new memory must match the timings set.