How do I find the right memory (RAM) for my computer

3 minute read

By now you will hopefully have chosen a processor and motherboard for your custom build PC, it’s now time to decide which memory modules to buy.

Although you will want to choose as much memory as you can afford, there are some other things to consider as well.

Random Access Memory (RAM) is where data is stored temporarily so that your processor can access the data quickly and do it’s processing. Logically, the more memory you have in your computer, the faster your computer will respond. This is especially important for memory hungry tasks like gaming and video/photo editing.

Let’s look at how to choose RAM for your build in 4 Steps:

Step 1: The memory type needs to match the CPU and motherboard

Look for the type of memory your motherboard and processor supports: DDR4, DDR3 or maybe DDR2.

The newest memory type is DDR4 which is marginally faster and uses less power. Newer memory usually has a larger price tag although prices fluctuate depending on how many people are buying.

DDR3 is the most widely used in current builds and is less costly but only supports older generations of processors and motherboards. I say older but in reality these components are still very much in use and are great for building a high spec self-build pc for a lower price tag.

There is another version of DDR3 labelled DDR3L which uses less power and can be used with the latest processors and motherboards. Now that DDR4 is becoming more available at the same kinds of prices, I can’t really see any benefit of buying DDR3L for your new build.

Even older is the DDR2 type memory which I will include here for anyone looking to build a budget pc with existing memory that they may have. For example I have lots of these old chips lying around and I could use them with a recycled motherboard to build a cheap internet surfing computer.

Step 2: Buy memory modules in kits

Computer memory works best in conjunction with the same speed and preferably with identical memory modules. These are packaged as memory kits like 8GB (2x 4GB) or 16GB (4 x 4GB) so that you can match the amount of identical memory in the number of DIMM slots on your motherboard.

So the 8GB kit would fill both DIMM slots on a motherboard with only two slots. Using this method means the memory runs in dual channel mode which increases the computer’s performance. One 8GB RAM module in only one DIMM slot does not perform as well. Different motherboards also support dual, triple and quad channel mode so check the motherboard to see which memory kit to buy.

Step 3: RAM clock speeds and how to choose the right ones

Just like the processor, memory runs at different clock speeds, check what speed the processor supports and match that to the RAM that you buy. These are the officially supported speeds by the processor but if you plan to be overclocking your CPU, you will also be increasing the clock speed of your memory. These speeds are listed on the memory with OC in brackets. The OC speed that the motherboard is capable of is also listed on the motherboard spec and you should be looking to match these potential speeds when buying RAM.

You’ll also see the Extreme Memory Profile (XMP) tag on this type of memory. This is an Intel technology that is used to set memory profiles in the motherboard’s BIOS for overclocking.

Step 4: Other features to look out for

CAS Latency

The CAS Latency (usually listed as CL or CAS) on the memory is a measure of latency. In simple terms it’s the time the memory has to wait to deliver data to the CPU, so look for low CAS values. In general unless you’re building a very high spec pc, latency values don’t really have a noticeable effect on performance. The memory’s clock speed is more important.

Heat spreaders

These are a great marketing tool used by manufacturers but in the real world, I haven’t noticed any performance improvements. Having said that, they can help to reduce how hot the memory get which should prolong the life of your RAM.