RAM isn’t the most exciting upgrade for your PC, but getting the right type – and enough of it – is essential if you want your system to achieve its full performance potential. Here’s our guide to choosing the right DDR4 modules, along with our selection of the best memory kits to suit a range of budgets.
How to choose the right RAM for your PC
You might imagine that computer memory is all much of a muchness, but in fact there’s a range of different memory types, speeds and timings to choose from – and that’s before we look at any extra features. Unless you’re pushing the limits of PC overclocking, however, there’s only a handful of factors you really need to worry about.
For a start, all modern CPUs and motherboards (for both AMD and Intel) now use DDR4 RAM, so unless you’re upgrading an older system you can immediately forget about DDR2 and DDR3 modules. You can almost certainly discount premium ECC memory too, assuming you’re not building a professional system that specifically requires it: this type of memory delivers exceptional reliability, but it’s overkill for a home computer.
What memory speed do I need?
The standard baseline speed for DDR4 is 2,133MHz, and for typical desktop tasks there’s no need to go any higher. However, if you’re running high-end games or productivity applications that tax your CPU to the fullest, standard DIMMs might struggle to keep up, resulting in a performance bottleneck. Step up to 2,666MHz or 3,000MHz modules and you’ll gain a measurable boost.
You can buy even speedier modules than this, but you quickly pass the point of diminishing returns: ultra-fast DIMMs are only worth the extra cost for hardcore enthusiasts seeking to overclock their CPUs and wring out every ounce of performance.
What about latency timings?
Just to confuse things, the operating frequency isn’t the only factor that determines the speed of a memory module. Each module also has its own timing or latency figures, which indicate how many clock cycles it takes for the RAM to carry out certain operations. Generally, four figures are given, with lower numbers representing faster performance.
Just remember that the length of a clock cycle is a function of the overall speed of the memory module. A memory kit with timings of 14-15-15-30 running at 2,400MHz isn’t necessarily faster than one with timings of 15-17-17-31 running at 3,000MHz.
What do descriptions like “PC4-24000C15” mean?
One reason why choosing the right RAM can seem so complicated is that manufacturers and retailers don’t all stick to the same way of denoting module types and speeds. A 3,000MHz DDR4 module with timings of 15-16-16-32 might be labelled as “PC4-24000C15”.
Thankfully, this isn’t too hard to decode. The PC4 prefix just means DDR4, and 24,000 expresses the speed in bits per second (to convert this to megahertz, simply divide by eight).
Finally, C15 refers to CAS latency, which is part of the timing information; effectively, it tells you that the module has timings of 15-?-?-?. Obviously, this isn’t the full story, but CAS latency is a good at-a-glance indicator of relative performance.
How much RAM do I need?
Having the right type of memory is important, but it’s also vital to have enough. For most non-gaming systems 8GB is ample, but for a gaming system or one that sees heavy use we’d suggest you go up to 16GB. Only exceptional workloads need 32GB, and if you’re doing that sort of task you’ll probably know about it. For most systems you’ll want to buy and fit modules in pairs to ensure peak performance; for AMD Threadripper and Intel LGA 2066 systems, buy in sets of four.
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The best DDR4 memory to buy in 2018
Crucial Ballistix Sport 2x4GB 2,400MHz: Best budget RAM
Price:£77 for 8GB | Buy now from eBuyer
If you’re putting together a basic PC for general desktop work and light gaming, an 8GB memory kit is all you need. Clocked at 2,400MHz, this Crucial kit won’t give you the very fastest performance in games, but the difference isn’t huge. With an Intel Core i7-8700K and Nvidia GTX 1080 Ti graphics card, we achieved average frame rate of 169fps – not too far behind the 182fps we got from the fastest modules on test.
Despite the low price, these modules also include heat spreaders to ensure they don’t overheat under heavy load and protect the electronics inside. They’re not the most attractive looking DIMMs around, but if you’re planning to install them in a regular desktop case then you won’t see them anyway.
HyperX Predator 2x8GB 2,666MHz C13: Best mid-range RAM
Price:£179.99 for 16GB | Buy now from Overclockers
This Kingston kit offers unusually low timings of 13-15-15-36 – so although it’s clocked at a mid-range 2666MHz, its performance matched some 3,000MHz and even 3,200MHz modules in our gaming tests.
Enthusiasts can even overclock these modules for an extra speed boost: we hit 3,000MHz without any problem, resulting in some of the best gaming results in our testing. The design is appealing too, with large black-on-black heat spreaders that look and feel the part. And it’s only slightly more expensive than a basic 16GB kit, making this a very tempting choice for gamers on a budget.
Corsair Vengeance LPX 2x8GB 2,400MHz: Best value RAM
Price:£139 for 16GB | Buy now from Amazon
If you’re looking for a balance of performance, capacity and price, Corsair’s 16GB kit could be the perfect solution. With a clock speed of 2,400MHz, these modules are 13% faster than bog-standard 2,133MHz DIMMs, and with reasonably tight timings of 14-16-16-31 they provide noticeably nippier performance than entry-level RAM.
The modules look fairly basic, with thin, short, painted (rather than anodised aluminium) heat spreaders. Still, go for the black option and they’ll quietly blend into the background, and their low height ensures they don’t interfere with any large CPU coolers.
And when it comes to value, the Corsair Vengeance LPX is very hard to beat. At the regular price of £160 it’s temptingly competitive – and right now it’s widely discounted down to an almost irresistible £139.
Corsair Vengeance RGB Pro 2x8GB 3,000MHz: Best LED RAM for enthusiasts
Price:£199.99 for 16GB | Buy now from Overclockers
If your PC case has a windowed side, why not jazz up the internals with a spectacular light show? These DDR4 modules each feature 10 bright RGB LEDs, in a strip that runs along the top of the module. The lights are powered directly from the RAM socket, so there’s no extra wiring required, and you can control the colours and patterns from Corsair’s excellent iCUE software. Matte black aluminium heat spreaders add to the premium look, and also provide heat dissipation and protection for the electronics.
The modules are available in a range of speeds, but we suspect they’ll appeal mostly to enthusiasts, who’ll want to go for the high-end 3,000MHz option. With reasonably tight timings of 15-17-17-35, these modules provide excellent overall performance, as well as making a real visual statement.
G.Skill Trident Z RGB 2x8GB 4266MHz: Best high-performance RAM
Price:£278.99 for 16GB | Buy now from Overclockers
Super-fast RAM isn’t necessary for most systems, but if you’re intent on pushing the limits of performance there’s no better choice than the Trident Z. Clocked at 4,266MHz, these modules are exactly twice as fast as basic DDR4, giving you masses of headroom to squeeze every last drop of performance from your system. Admittedly with timings of 19-19-19-39 you lose a little in latency, but the blistering clock speed more than makes up for that.
You also get a premium brushed aluminium heat spreader on either side of each module, along with RGB lighting across the top – and it’s all impressively affordable. Sure, it’s around £100 more expensive than a mid-range 2x8GB kit, but that’s not bad for absolute top-of-the-line hardware. If only graphics cards were priced the same way...