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Intel Core i9-12900KS review: Intel’s fastest gaming CPU yet

But you should probably stick to the Core i9-12900K... or a good Core i5

If Intel’s recent takeover of the RPS best gaming CPUs guide wasn’t indication enough, their latest 12th Gen Alder Lake chips are the real deal – especially on pure games performance. This should make the newly launched Core i9-12900KS, in a way, the realest deal of all: it’s structurally identical to the Core i9-12900K, originally the top-spec CPU in the series, but made with an even more discerning binning process. A component of the highest quality components, if you will, and as such can brush past the Core i9-12900K’s maximum boost clock speed of 5.2GHz to reach a scorching 5.5GHz.

Higher per-core speeds are usually good news for games, and it’s not just at the top end where the Core i9-12900KS makes improvements: its eight bigger, badder Performance core (P-cores) get a 200MHz base clock increase up to 3.4GHz, and its eight smaller Efficiency cores (E-cores) rise 100MHz up to 2.5GHz. The final results very often back up Intel’s claims of this being the “world’s fastest desktop processor,” though it’s also kind of the CPU version of the RTX 3090 Ti graphics card: technically better, but perhaps not by a big enough margin to justify over more affordable alternatives.

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Sadly, due to sampling delays I wasn’t able to test the Core i9-12900KS alongside the AMD Ryzen 7 5800X3D, which the red team also claim to be the planet’s fastest gaming CPU (albeit by leveraging a very different method: loading up on cache instead of maxing out core speeds). What I can tell you is that the Core i9-12900KS smokes all other know Ryzen and, indeed, Intel Core CPUs as a desktop multitasker. In the Cinebench R20 benchmark, its single-core score of 811 and multicore 11,019 put it far ahead of both the Core i9-12900K (756 and 10,519 respectively) and the AMD Ryzen 9 5950X (639 and 10189).

They also neatly demonstrate both of the newer Intel chip’s big assets: the higher core clock speeds are responsible for the monster single core performance, while its multicore prowess comes from the signature Alder Lake combination of P-cores and E-cores. As with most of its 12th Gen stablemates, the Core i9-12900KS can more efficiently shunt little chunks of workload onto the cores that are best suited for them – demanding work goes to the P-cores, lighter jobs go to the E-cores. If you also need your gaming PC to juggle media editing or heavy coding, the benefits are self-evident.

A bar graph showing the Intel Core i9-12900KS' games benchmark results, alongside those of competing CPUs.
A bar graph showing the Intel Core i9-12900KS' games benchmark results, alongside those of competing CPUs.

As for games specifically, the Core i9-12900KS comes out on top more often than not. Have a look at these benchmark results, recorded with an RTX 2080 Ti GPU: you can see for yourself that it consistently edges ahead of both the Core i9-12900K and Ryzen 9 5950X. The latter was tested using DDR4 RAM, not DDR5 like all four of the 12th Gen Intel CPUs, but I’ve found that DDR5 is neither significantly better nor worse than DDR4 on current hardware and games.

Other than a freakishly good Assassin’s Creed Valhalla performance by the Intel Core i5-12400F (I’ve re-tested this several times and yes, it’s legit), the Core i9-12900KS either leads or matches its rivals in every single game. It’s definitely the fastest gaming CPU that Intel have ever made; the fastest in the world? That’s up to the Ryzen 7 5800X3D, but I’d say the Core has a very good shot.

There is a difference, mind, between being the fastest and being the best. As it was with the RTX 3090 Ti, the underlying fun-killer is money: when the Core i9-12900KS costs £720 / $750, about £120 / $150 more than the Core i9-12900K, you’d expect the gaming performance gap to reflect that difference.

An Intel Core i9-12900KS CPU being held between a finger and thumb.

It doesn’t. It’s all well and good averaging 10fps more than the S-less model in Shadow of the Tomb Raider, but at 160fps and above you can hardly see the difference. And in almost every other game, there’s either a negligible 2-3fps difference, or none at all. Assassin’s Creed Valhalla widens the Core i9-12900KS’ lead a little, but an extra 6fps just ain’t worth another £120.

And that’s just comparing it to the fellow Core i9. Yes, technically they tend to be a few more FPS behind, but the relatively cheap Core i5-12600K and Core i5-12400F are competitive with the Core i9-12900KS in everything short of Forza Horizon 4. And, perhaps, Shadow of the Tomb Raider, though in both cases the high frame rates mean 10-20fps discrepancies aren’t as visible as they would be at lower levels. Elsewhere, it’s another bunch of single-digit differences, which makes the value proposition of the Core i9-12900KS even worse.

Besides paying more than you’d need to, choosing the Core i9-12900KS would also mean using more power than you’d need to. Its base power usage – not even maximum draw – is 150W, 25W more than the Core i9-12900K and Core i5-12600K and a gluttonous 85W more than the Core i5-12400F. The Core i9-12900KS is unlocked for overclocking, unlike the Core i5-12400F, but that would also put you into a tricky situation with heat.

An Intel Core i9-12900KS CPU installed in a motherboard.

I tested the Core i9-12900KS with an Asus ROG Ryujin II 360, a fairly expensive (but effective) AIO watercooler. When gaming, it doesn’t get dangerously hot, with the warmer P-cores most often keeping in the 44-60°c range. But that’s up to 10°c hotter than the Core i9-12900K, and the P-cores’ 71°c peak was higher too. So the cheaper chip will be easier to overclock on liquid cooling, though both CPUs could also easily hit 100°c (what I like to call the uh-oh temperature) during Cinebench R20 runs. At stock speeds!

I’d say this isn’t too big a deal if you’re just building a gaming PC, rather than a multi-purpose workstation, though if that’s the case then you’re better off forgetting about the Core i9s and just getting a Core i5-12600K (or Core i5-12400F) instead. The Core i5-12900KS’ allure as a carefully crafted record-setter isn’t as strong as the satisfaction you’ll get from saving hundreds on a processor with essentially identical performance.

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