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

Question

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

Answer

Determining the type of memory required

By 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. Thankfully today even if you don't have your product documentation you can still find it online through the computer manufacturers web site or motherboard manufacturer web site.

• How do I find what computer motherboard I have?

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

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

In the above example you can see this motherboard supports DDE SDRAM DIMM at speeds of 400/333/266.

Alternatively you can 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

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 will run at the speed of the lowest speed memory in the computer. The computer will still work, but if you get faster memory and have slower memory in the computer it will run at the speed of the slower memory.

Error-checking:

Does the computer require error-checking memory? For example: Parity or Non Parity / 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 will cause no issues with the computer, only increase the price on the memory when compared with memory with no error checking.

Voltage:

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

Contact material:

The contact material on the memory is important for users who are looking to purchase memory. Memory modules will be coated in either gold or tin to match the slots that they're connected into. Mismatching the memory contact material with the motherboard memory slot contact material can cause issues to arise, 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.

Before purchasing memory

Make sure you have the available slots

Make sure the computer has the available 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.