What type of computer memory to use in a memory upgrade

Updated: 04/12/2021 by Computer Hope
Computer memory aka RAM

The following tips and information help you decide what type of memory to buy as an upgrade to your computer.

Determining the type of memory required

If you're considering a memory upgrade, the first step is to determine which memory is currently installed, and what types of memory your motherboard supports.

Use a third-party tool or service

One option is to use a third-party software utility or online service that provides details about the components in your computer. These utilities can scan your computer and give a detailed report of all installed hardware, including memory. For example, the Crucial System Scanner is a free utility that scans your computer, and give you details about your installed memory any available memory slots.

Documentation

By far, the best method of determining the memory (RAM) to use with your computer is through the computer or motherboard manufacturer documentation. If you do not have your product documentation, you can also find it online through the computer manufacturers or motherboard manufacturer website.

For example, your motherboard documentation may list something similar to the example below.

Supports DDR4 2666/2400/2133 SDRAM.
Supports up to 4 non-ECC unbuffered DIMM.
Up to 8 GB per DIMM, with a maximum total memory size up to 32 GB.

In the example above, you can see the motherboard supports DDR4 SDRAM DIMM at speeds of 2666, 2400, and 2133 MHz.

Visually examine the memory

512 MB DIMM example of memory stick

You can also open the computer. Taking precautions not to cause ESD (electrostatic discharge), remove one of the memory sticks and physically examine the memory for any identifying stickers or printed labels.

What to look for in memory

Below is a short list of what to look for or determine when trying to determine the memory your computer needs.

Memory type

What type of memory does the computer use? Some examples of the different memory types include DDR-SDRAM, DDR2-SDRAM, DDR3-SDRAM, DDR4-SDRAM, DIMM, DRAM, EDO, FPM, SDRAM, LIMM, RDRAM (RAMBUS), RIMM, SIMM, and SODIMM. Today's computers usually use a variant of DIMM/SDRAM memory.

Amount of pins

How many pins does the computer accept? 72-pin, 30-pin, 168-pin, 184-pin, or 240-pin? The answer depends on the type of memory.

Speed of memory

There are two primary measurements of memory speed.

  • The "speed" of memory generally refers to how many times, per second, the memory can read or change its data per second. This speed is measured in MHz and strongly affects the overall performance of your CPU.
  • Latency is the (very short) amount of time it takes for memory to respond to information requests, access data stored in memory, and send that data to the CPU. Latency is measured in nanoseconds (ns).

Although latency is an important metric, differences in latency are relatively minor in compatible RAM modules. When making a decision about what memory to use in your computer, the speed measured in MHz is generally the more important number to consider.

Note

If you install memory sticks of varying speed ratings in your computer, the lower speed is used, and you don't receive the potential benefit of the faster module's speed. When possible, use RAM modules of equal speed. Ideally, you want all RAM installed in your computer to be identical.

Error-checking

ECC (error-correcting code) memory is used in servers and professional workstation computers. It sacrifices some of its speed to provide error protection. It quickly checks to make sure there were no errors whenever data is modified in RAM.

Errors may naturally occur in RAM because of electromagnetic interference or hardware faults. As a result, bits can become "flipped" in RAM; some bits that should be set to 1 are set to 0, or vice versa. These errors are usually not fatal for casual applications like video games or web browsing. For example, a single pixel in the background of a video game is the wrong value, you might not notice or care. However, for professional applications that require a high degree of accuracy, such as financial transactions or scientific calculations, ECC is a necessary feature. ECC doesn't prevent errors entirely, but it reduces their probability to nearly zero.

Not all motherboards support ECC, and those that support ECC are usually more expensive. The ECC RAM modules are also more expensive than non-ECC RAM of equivalent speed. If you're not sure you need ECC, you probably don't. Building a computer without ECC support usually means getting more bang for your buck in terms of your computer's performance.

Voltage

What are the voltage requirements? Make sure you determine the voltage requirements of the memory (e.g., 1.5v, 1.8v, or 2.5v).

Contact material

The contact material on the memory is also important when considering buying computer memory. The contact area is coated in either gold or tin and should match the material of the memory slots. Mismatching the memory and memory slot contact material can cause corrosion.

Proprietary

Finally, is the memory in your computer proprietary? If not, is there memory your computer manufacturer recommends? If you have a more recent computer (made in the last five years), this should not be a concern.

Other terms

See our memory terms page if there is any other jargon that is confusing you.

Before purchasing memory

Make sure the computer has the available memory slots for the memory you are installing. For example, if you are installing an additional 8 GB of memory in the computer and plan on using two 4 GB memory sticks, make sure you have two available slots. If you do not have available slots, you can remove pre-existing memory and install new memory. However, any memory removed is subtracted from your total. Below is an example of a possible scenario.

Computer memory slots

A computer has 4 GB of memory, from four different 1 GB sticks of RAM and has no more available slots. If you want to upgrade to a total of 8 GB, the four 1 GB sticks would need to be replaced with four 2 GB sticks. Alternatively, two of the 1 GB sticks could be replaced by two 4 GB sticks.

Tip

When dealing with memory, 1 GB = 1,024 MB

Installing the memory

When you're ready to install the memory you purchased, follow the steps and precautions in our guide linked below.