What type of computer memory to use in a memory upgrade?

Determining the type of memory required
What to look for in memory
Before purchasing memory
Installing PC computer memory

Determining the type of memory required

Documentation

Computer memory aka RAMBy far the best and recommend method of determining the type of memory (RAM) that should be used with your computer is through the computer or motherboard manufacturer documentation. If you don't have your product documentation you can still find it online through the computer manufacturers or motherboard manufacturer website.

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

Supports DDR 400/333/266 SDRAM
Supports up to 3 unbuffered DIMM or 2.5 volt DDR SDRAM
Up to 1GB per DIMM with a maximum memory size up to 3 GB

In the above example, you can see this motherboard supports DDR SDRAM DIMM at speeds of 400, 333, and 266.

Use a third-party tool or service

Another option would be to use a third-party software utility or online service that can provide details about the components in your computer. This type of utility will usually scan your computer and provide a detailed report of everything in your computer, including specifications for the type of memory your computer has in it. We suggest using the Crucial System Scanner utility, which is a free utility to scan your computer and give you computer memory details including available memory slots.

Visually examine the memory

512MB DIMM example of memory stick

Finally, you can also open the computer being aware of ESD, remove one of the memory sticks currently installed in the computer and physically examine the memory for any stickers or printed labels identifying the memory.

What to look for in memory

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

Memory type

What type of memory does the computer use? Some examples of the different memory types include: DDR-SDRAM, DDR2-SDRAM, DIMM, DRAM, EDO, FPM, SDRAM, LIMM, RDRAM (RAMBUS), RIMM, SIMM, and SODIMM. Often many computers today 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, 240-Pin, etc. This will often be related to the type of memory.

Speed of memory

Earlier memory was listed in nanosecond (ns) speeds such as 70ns, 60ns, 10ns, etc. However, today speeds of memory are often expressed in MHz such as 266MHz, 333MHz, 400MHz, 500MHz, 533MHz, 667MHz, 800MHz. Make sure you get the correct speed of memory for your computer.

Note: If you mix the speeds of your memory in your computer the computer runs at the speed of the lowest speed memory in the computer. Although the computer is still going to work, you are paying more for a higher speed that is not being utilized.

Error-checking

Does the computer require error-checking memory? For example, Parity or Non Parity (i.e., ECC or Non-ECC). The option between the two is often only required on older computers using SIMM or older computer memory standards. New memory and computers only use memory with error checking. If you're uncertain going with parity, ECC, or other memory that has error checking does no harm to the computer it's only going to be slightly more expensive when compared to non error checking memory.

Voltage

What are the voltage requirements? Make sure you determine the voltage requirements of the memory, e.g. 1.8v, 2.5v, etc.

Contact material

The contact material on the memory is also important when considering purchasing computer memory. Memory modules will be coated in either gold or tin and should match the material of the memory slots. Mismatching the memory and motherboard memory slot contact material can cause issues to arise such as corrosion, not always immediately.

Proprietary

Finally, is the memory in your computer proprietary, and if it is not, is there a manufacturer that your computer company recommends? Often today this is no longer an issue for desktop computers and all major memory should work in desktop and the majority of laptops. Click here for a listing of different memory manufacturers.

Other terms

You can also find a full listing of all terms relating to computer memory on on our memory definitions.

Before purchasing memory

Computer memory slots

Make sure you have the available slots

Make sure the computer has the available memory slots for the memory you're installing in the computer. For example, if you're installing an additional 1GB of memory into the computer and plan on using two 512MB memory sticks make sure you have two available slots. If you do not have the available slots to install memory, you can remove pre-existing memory and install new memory. However, memory that is removed will be subtracted from your total. Below is an example of a possible scenario.

Computer has 512MB of memory, from four 128MB sticks of RAM using all available four slots to install RAM. User wants to have a total of 1GB of memory so each of these sticks would be removed and replaced with either four 256MB sticks or two 512MB sticks.

Installing the memory

Additional information