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Core i9 11900K and Core i5 11600K: memory bandwidth analysis

What difference does RAM make to 11th-gen Core?

With the launch of its 11th-gen desktop processors, Intel has finally allowed motherboards built around its cheaper H570 and B560 chipsets to access memory "overclocking", something that was previously only allowed for expensive Z-series boards like Z390 and Z490. We put overclocking in quotes there because this restriction meant that users weren't even able to run their RAM at its rated XMP speeds if this surpassed the previous limit of 2933MHz for Core i7/i9 processors or 2666MHz for Core i3/i5 CPUs - a ridiculous situation, if you ask us.

By relaxing these restrictions, users on more constrained budgets are better able to take advantage of modern high-speed RAM, including the large amount of good value 3200MHz and 3600MHz kits on the market. We've got to give Intel credit for finally making the long-requested change, although we suspect AMD's long-standing policy of not restricting memory speeds by platform (and Ryzen's steady market share increase) is the more likely impetus for Intel's shift than a sudden onset of charity from Team Blue.

In any case, a greater number of motherboards supporting higher RAM speeds means that it's more critical than ever to know how much extra performance you can actually unlock from a fast memory kit. To answer this, we tested three games at two common frequencies, entry-level ~3000MHz and a common high-tier option, 3600MHz. We're using the exact same sticks and the same timings for these tests (16-16-16-36); just the frequency has shifted here.

First up is Ashes of the Singularity, a great DX12 title that absolutely lives and dies on CPU performance, where fast RAM typically sees noticeable performance improvements. Both the 11900K and 11600K see a small single-digit percentage uplift, four per cent for the 11900K and five per cent for the 11600K. It's also worth noting that the 11900K runs this game ten per cent faster than its little brother - not a massive gap, given the price differential. The gap from the 10900K to the 11900K is even larger, at 19 per cent - better than what you'd expect given Intel's quoted 19 per cent IPC uplift and the loss of two cores - and there's a similar gen-on-gen margin for the Core i5. The 11900K also holds a 10 per cent lead over the 5900X, despite having far fewer cores - not bad, Intel.

Ashes of the Singularity: CPU Test

Far Cry 5 next. This is a single-core-reliant title, so we expect to see a small but noticeable CPU gain from higher RAM - and that's exactly what we get; around one per cent for the 11900K and two per cent for the 11600K. Not much to write home about here, but it's at least measurable.

Far Cry 5: Ultra, TAA

Crysis is architected very differently, using a much larger number of cores than Far Cry 5, and shows even less of a difference from RAM upgrades. It's true to form here, with a nigh-identical result for the 11900K and only a one per cent boost for the 11600K. Here, whatever RAM you've got will be just fine.

Crysis 3: Very High, SMAA T2X

Next we look at another way to glean some extra performance - the Adaptive Boost feature exclusive to the Core i9 11900K and the graphics-free Core i9 11900KF.

Intel Core i9 11900K and Core i5 11600K analysis

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Will Judd avatar

Will Judd

Deputy Editor, Digital Foundry

A bizarre British-American hybrid, Will turns caffeine into technology articles through a little-known process called 'writing'. His favourite games are Counter-Strike, StarCraft and Fallout 2. Will also tweets the latest tech deals at @DealsFoundry.


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