Custom PC

REVIEW: Intel Core i9-12900K

By Antony Leather. Posted

This article appears in Custom PC magazine. Pick up the latest issue to read more about Intel's Alder Lake CPUs, with deep tech dives and more reviews.

It’s been a long time coming, but Intel has finally taken a giant leap forwards in terms of architecture, CPU design and manufacturing – Alder Lake is here at last. We’re finally dealing with a desktop 10nm CPU from Intel now and, rather than just using this opportunity to add more cores, Intel has made some interesting changes to its CPU design.

There are now two different types of cores in this hybrid CPU design, with Intel attempting to provide more performance at lower power levels and have different cores designed to different tasks. There are P-cores and E-cores – the former deal with high-performance tasks, and the latter aid lower-power and background tasks, while providing a general boost to multi-threaded workloads.

If you think this sounds a nightmare in terms of thread management in Windows, you’d be right, but Intel has worked with Microsoft to enhance the thread scheduling capabilities in Windows 11, and its 12th-gen CPUs also now include a feature called Thread Director.

This intelligently manages workloads to improve performance and lower power consumption based on priorities, pushing demanding workloads onto P-cores and lighter tasks onto others. This should work independently of Windows 11, but Intel says that Windows 11 will definitely offer additional performance compared with other operating systems, for now anyway.

Intel Core i9-12900K

There are quite a few differences between the cores too. E-cores lack Hyper-Threading, so even though the Core i9-12900K has 16 cores made using a 10nm manufacturing process under the hood, only the P-cores feature Hyper-Threading. As a result, the Core i9-12900K has a total of 24 rather than 32 threads. This core differentiation extends to overclocking too, as both P-cores and E-cores can be overclocked separately and have very different limits.

This flagship CPU also retails for £579 inc VAT, which is a fair bit less than the current price of AMD’s mighty 16-core Ryzen 9 5950X, but a little more than the 12-core Ryzen 9 5900X. The Intel CPU can hit 5.2GHz using Turbo Boost Max technology on its P-cores, but only 3.9GHz on its E-cores.

We didn’t see the P-cores top 5.1GHz in CPU-Z, but we were using very early drivers and BIOS versions. The E-cores appeared to run at their maximum 3.9GHz most of the time, though, and unlike the P-cores, this was across all cores too. The P-cores fell to 4.9GHz in multi-threaded workloads, though, while the E-cores dropped down to 3.7GHz.

Memory support is another major tweak and you’ll be glad to know that both DDR4 and DDR5 are supported, with plenty of DDR4 motherboards from which to choose. This CPU officially supports the latter at 3200MHz, while DDR5 support starts at 4800MHz. The Core i9-12900K also sports a massive 30MB L3 cache, along with 14MB of L2 cache, plus PCI-E 5. What’s more, the K-series Alder Lake CPUs also get Intel UHD Graphics 770, which is based on Intel’s Xe architecture.

Intel Core i9-12900K

Performance

The Core i9-12900K’s performance is stellar. It’s the first CPU to crack 80,000 points in our image editing test and it even beat the 16-core Ryzen 9 5950X in our heavily multi-threaded video encoding test, with a massive score of 1,117,658 compared to 1,061,730 for the AMD CPU – it’s also in a different league to the Ryzen 9 5900X in this test.

The Handbrake result nearly doubles the score from the Core i9-11900K too. The system score was just short of 400,000 points, with a clear lead over the 5950X and miles ahead of the Core i9-11900K, which only managed 263,567.

The 12900K also smashed Cinebench R23 with a multi-threaded score of 27,579, which was again nearly double the score of the Core i9-11900K and faster than the Ryzen 9 5950X by a few thousand points. As if stellar multi-threaded performance wasn’t enough, It had a huge single-threaded score of 1,992 as well – hundreds of points faster than any older CPU.

It’s even blisteringly fast in games, adding up to 10fps to the average frame rate of any AMD CPU in Far Cry 6, but for some reason it was a little behind the other two 12th-gen CPUs on the 99th percentile results. It was faster than any AMD chip in Dirt 5 as well.

Meanwhile, power consumption has been a sore topic for Intel lately, but the Core i9-12900K was restrained at stock speed, hitting 248W at load, which was barely any more than the Ryzen 7 5800X, although this was a little higher than AMD’s flagship Ryzen 9 5950X. Still, it’s a vast improvement compared to the 360W the Core i9-11900K drew at stock speed.

We didn’t have much time to overclock the Core i9-12900K before we had to get the magazine printed, but we found the 12900K has similar overclocking potential to 10th and 11th-gen CPUs on the P-cores, with us ending up at a stable all-core frequency of 5.1GHz with a 1.36V vcore. We could only get the E-cores to stick at their maximum 3.9GHz frequency across all cores, which was at least a 200MHz boost above the all-core stock frequency we observed.

These tweaks saw the 12900K gain an extra 2,000 points in the image editing test, which went up to 82,361, and it held its lead in the video encoding test, with a higher score of 1,120,269 compared to the Ryzen 9 5950X’s overclocked score of 1,113,608. The system score sat at 399,954, again more than a match for the AMD CPU and a long way ahead of the Core i9-11900K.

Overclocking also benefited games, with the minimum 99th percentile in Far Cry 6 hitting 108fps, which was over 10fps higher than any AMD CPU and its average of 143fps leading the pack. Overclocking did result in our system drawing 320W from the mains at load, but that’s still 11W less than with an overclocked Ryzen 9 5950X.

Conclusion

We honestly weren’t sure what to expect from Alder Lake, but the proof is in the pudding and the Core i9-12900K is an absolute monster while remaining relatively power-frugal too, especially compared with previous generations.

In games, it proved to be significantly faster than AMD anywhere that was remotely CPU-bound, although in our test games it didn’t offer much benefit over the other two 12th-gen CPUs on test, which clearly offer better value for gamers.

In content creation, the 12900K absolutely flies, matching or bettering the Ryzen 9 5950X in multi-threaded tasks and offering much more performance in any single or lightly threaded tasks. This is despite it costing less than the AMD CPU, which was still retailing for close to £700 at the time of writing.

If you’re just gaming and dabbling occasionally in content creation, then the Core i5 or Core i7 12th-gen CPUs offer better value and still provide great multi-threaded performance. However, if you need the best multi-threaded grunt for a mainstream desktop PC, the Core i9-12900K is for you and as a bonus it’s also a fantastic CPU for gaming. Welcome back, Intel.

Verdict
A devastatingly fast CPU across the board – it’s faster and better value than any CPU AMD currently offers.

Price
£579 inc VAT

Scores
PERFORMANCE 49/50 | FEATURES 14/15 | VALUE 32/35 | OVERALL 95%

ALDER LAKE

  • King of the hill in games
  • Superb multi-threaded performance
  • Costs less than £600

LAKE PLACID

  • Overclocked Ryzen 9 5950X faster in some tasks
  • Requires new motherboard
  • CPU socket needs new cooler or adaptor

SPEC
Base frequency P-core 3.2GHz, E-core 2.4GHz
Max boost frequency P-core 5.2GHz, E-core 3.9GHz
Core Alder Lake
Manufacturing process 10nm
Number of cores 8 x P-cores, 8 x E-cores, (24 threads)
Hyper-Threading Yes (P-cores only)
Cache 30MB L3, 14MB L2
Memory controller Dual-channel DDR4 3200MHz and DDR5 4800MHz
Packaging LGA1700
Thermal design power (TDP) 125W
Features Turbo Boost Max Technology 3, Turbo Boost 2, FMA3, F16C, SHA, BMI / BMI1 + BMI2, AVX-512, AVX2, AVX, AES, SSE4a, SSE4, SSSE3, SSE3, SSE2, SSE, MMX

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