How To Build A PC

Step 5: Select Memory

When it comes to picking memory for your build, there are numerous options. If you find the whole process overwhelming, the easiest answer is to simply buy 1.5-volt DDR3-1600 modules with CAS 9 timings or 1.2-volt DDR4-2133 modules with CAS 15 timings, depending on your platform. The DDR3 sticks are universally supported on many motherboards and the DDR4 sticks are universally supported on Intel’s X99 and Skylake platforms. Even better, both are inexpensive and readily available as both 4 and 8GB sticks. If that solution is a bit too simple for you then checkout our Best Memory column, which provides recommendations for both DDR3 and DDR4 kits.

There are noticeable performance benefits for similarly-priced DDR3-1866 (PC3-14900), particularly if you're using a CPU's on-die graphics engine for gaming, and this speed functions normally, even with processors that are not officially designated to use it (primarily older models or low-energy platforms). Furthermore, the same easy benefits of DDR3-1866 are even available with most DDR3-2133 kits and modern performance-oriented processors.

However, the problem with recommending faster memory kits is that they often require at least some manual configuration. If you're not comfortable tooling around in your motherboard's firmware, they might actually drop you to lower performance levels.

You see, Intel’s XMP (eXtreme Memory Profiles) technology facilitates extended memory settings beyond the basic automatic-configuration technology called SPD. Although XMP originally allowed motherboards to set overclocked options like nonstandard voltages and data rates, most of today's XMP-capable modules operate at standard voltage levels and frequencies. Still, when you first boot up, they typically default to either DDR3-1333 or -1066. Going higher requires that you manually enable an XMP profile. Even some DDR3-1600 modules employ XMP (rather than SPD values) to achieve their rated performance levels, and this is particularly true of reduced-latency (CAS 7, CAS 8) modules.

Memory faster than DDR3-2133 is usually expensive and not really required. Our tests have shown that DDR3-2400 is barely beneficial, and only in situations where you're leaning on integrated graphics. We've even seen data rates above 2400 MT/s hurt performance as the motherboard attempts to increase stability.

Those who like taking advantage of the latest technologies will be thrilled to hear that Intel’s latest generation Skylake CPUs officially support DDR4 memory. Better yet, the price of DDR4 has fallen to the point where it’s not really that much more expensive than a similar sized and performing DDR3 kit. Unfortunately, those loyal to AMD are either going to have to migrate to an Intel system or wait for AMD’s next generation of CPUs before they can make use of DDR4.

In terms of memory quantity, we recommend no less than 4 GB even for the cheapest of systems, though 8 GB will yield a noticeable performance boost. For those who plan on gaming, we recommend at least 8 GB of RAM if you’re on a budget, with 16 GB recommended for those who can spare the increased cost. Finally, if you plan on doing any sort of photo/video editing or heavy multitasking, we recommend you start at 16 GB and add more if you find that you need it.

Our memory reviews show a wide range of options, and buying name-brand modules with lifetime warranties from reputable vendors is good insurance against unexplained system instability.

MORE: Best Memory
MORE: All Memory Articles

MORE: Memory in the Forums

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  • James_39
    Selecting the case is a bizarre thing to have in Step 1.Surely that would be best placed once all other components, including accessories, have been factored in? Otherwise you end up selecting components purely on the basis they fit in your case, not forgetting that some (most) cases don't support water cooling kits/pipes etc mentioned in Step 8.