Computer basics

How to choose the right RAM for your PC

Every component in your computer is important, complex, and has more specifications than most folks are familiar with. Your RAM, or Random Access Memory, is no exception to this. Generally, people know that “more RAM is better,” but that’s not the extent of it. It’s also not always accurate. Let’s take a look at what you need to know about choosing the right RAM for your PC.

DDR

Modern RAM comes with different numbered DDR identifiers. For better or worse, this has nothing to do with Dance Dance Revolution. In RAM, DDR stands for “Double Data Rate,” with the appended number (as in “DDR4”) indicating the generation of this double data rate standard. Early computer RAM was typically referred to as just DRAM, which stands for Dynamic Random Access Memory. Most RAM is still effectively DRAM, just with better circuit designs that enable memory to work more quickly and with higher capacity. First, they added a clock signal interface so the DRAM could sync up with other parts of the system, becoming known as SDRAM. Then DDR was developed to double the amount of data bandwidth available to the rest of the machines and you, its user.

From there came DDR2, then DDR3, and now most current devices utilize DDR4 RAM. DDR5 does exist as a memory standard, and you may find it mentioned in graphics cards, but DDR5 RAM modules aren’t quite ready for the market at the time of writing this article. Whatever the case, though, your motherboard and CPU are going to be the major determining factors on what kind of DDR RAM you need for your PC, so know those specifications before choosing your RAM.

Capacity

This is the part many people are familiar with: More RAM is good, less RAM is bad. RAM capacity is the major specification folks are looking for when purchasing. Generally, having 8GB of RAM will provide a better computing experience than 4GB of RAM. Video games will include RAM capacity in their recommended system requirements. Various software will have their own minimum requirements for available memory. This is all capacity.

You cannot just purchase as much RAM as possible, however. A 32-bit process and operating system could only make use of up to 4GB of memory, so the additional RAM on such a system effectively goes to waste. Most modern systems are 64-bit, which can theoretically handle up to 4 petabytes of memory, albeit most modern PC CPUs tend to be capped at anywhere between 32GB and 256GB of memory. As mentioned above, you’ll want to refer to your CPU and motherboard specifications to determine what RAM capacity your system can handle—then following the edict of “more is better” aim for the higher end of that spec.

Speed

This is the aspect of RAM that gets a bit complex. There are two main factors behind what makes RAM considered fast: frequency and timing.

First is the RAM’s frequency, which is far too commonly referred to as the speed. When looking at RAM products, you might find it listed as DDR4-3200 or DDR4 2666 MHz. Those four-digit numbers are the frequency of the RAM. Your memory is constantly doing reading and writing cycles with your currently loaded data, and that frequency is referring to how many times per second the memory is going through that cycle. DDR4-3200 is referring to a 3200MHz frequency cycle, which translates to about 3.2 billion read/write cycles per second. So, generally speaking, a higher frequency is better, but note that some CPUs and motherboards may not support some frequencies effectively, and may require additional research if you’re looking to maximize your performance. Additionally, the price for high-frequency RAM tends to ramp up very quickly.

Then there’s timing, also known as Column Access Strobe latency or CAS latency, which is a measurement of the delay between your RAM modules receiving a command from the CPU and the RAM actually executing that command. CAS latency is typically listed as a series of numbers, such as 18-22-22-42, which is actually referring to a series of timing values beyond just CAS latency. Typically, the timing order is CAS Latency – Row Address to Column Address Delay – Row Precharge Time – Row Active Time. Basically, lower numbers are better. There is much more depth to go into here, but generally speaking, differences in timing aren’t going to make a huge impact on your experience with modern auto-detect settings and memory controllers on your motherboard and CPU.