Technology Blog

The best memory for Skylake-X


Most X399 motherboards now support a mix of kits with frequencies of 3000MHz and higher. However, Intel has nailed memory support with the X299 launch straightaway.

best memory for Skylake-X

The XMP profile worked on every board we used this month, with all of them heading straight into Windows at 3200MHz with four DIMMs in quad-channel mode.

But what speed of memory should you choose for your X299 system? Unlike X99, the X299 chipset supports up to 2666MHz DDR4 memory as standard, although there may still be a few cheap 2133MHz kits lying around that could save you some cash.

If you shop around, though, you’ll find that 3000MHz and even 3200MHz kits are often not that much more expensive. We spotted 16GB quad-channel Corsair Vengeance LPX kits that showed less than a difference between 2133MHz and 3200MHz kits, and the difference wasn’t much greater with 32GB kits either. Another issue is that many of the latest kits, such as Corsair’s Vengeance RGB models, are only available in 3000MHz or higher configurations.

So does a higher memory frequency always significantly improve performance on the X299 platform, or is there a sweet spot where you get the ideal bang for your buck? Will spending more money net you more frame rates, or shorter rendering times? To find out, we pitched four 32GB sets of quadchannel memory against one another in some of our benchmarks to see which frequency provided the best performance and value.

In our image editing test, the results were very similar, with very little difference between 2133MHz and 3200MHz memory.

The biggest jump was between 2133MHz and 2666MHz, with results above this clock speed being within the variation you would expect in this test.

Our heavily multi-threaded Handbrake video encoding test, though, saw a noticeable improvement all the way up the scale, albeit with diminishing returns as you approach 3200MHz. The multi-tasking test saw a very similar set of results.

best memory for Skylake-X performance

The biggest leap by far was between 2133MHz and 2666MHz, but above this frequency, you don’t gain anywhere near as much in each jump in frequency. Even so, 3200MHz RAM does still give you a noticeably higher score than 3000MHz memory.

Overall, the fastest result is –not surprisingly – with 3200MHz memory, but by a comparatively small amount compared to 2666MHz, with scores of 259,075 compared to 256,791. There was an appreciable difference, though, between the 250,605 score of the slowest RAM.

The sweet spot in terms of our benchmarks is 2666MHz, although at current prices, you might as well get the better performance on offer from a 3200MHz kit anyway.

Elsewhere, the results were even more varied. In Cinebench, there was next to no benefit of having RAM faster than 2666MHz, but in Ashes of the Singularity: Escalation’s CPU-focused benchmark, the game scaled all the way as the memory frequency increased. There were signs of diminishing returns in the average frame rate, but the results were still higher.

Clearly, if you’re spending hundreds of pounds on a CPU and potentially thousands of pounds on an X299 system as a whole, while 2666MHz is the sweet spot in some tests, there are tangible improvements by going for 3200MHz RAM. With some quad-channel kits costing barely £20 more for 3200MHz compared with 2666MHz memory, this small premium is definitely worth paying.