Core i9-12900KS Review: Intel’s Fastest Alder Lake CPU Tested

Over the last few generations of its mainstream desktop processors, Intel has released “Special Edition” models, which are functionally similar to that generation’s flagship CPU, but with goosed clock speeds to boost performance. The same is true of the Alder Lake-based 12th Gen Core processors. When Alder Lake initially hit the scene, we had the opportunity to evaluate the then top-end Core i9-12900K and its little brother, the excellently efficient Core i5-12600K. Fast forward a few months though, and Intel took the 12900K, injected a little adrenaline, cranked up the clocks, and the Core i9-12900KS was born.

Intel bills the Core i9-12900KS as “the ultimate processor for enthusiasts and gamers”. And Intel can certainly make that case. Alder Lake has proved to be an excellent performer, with class-leading single-threaded performance and responsiveness, with highly-competitive multi-threaded performance across a variety of workloads. The rest of the platform and its companion 600-series chipsets further enhance the story, with leading-edge IO and connectivity options abound.

What Makes The Core i9-12900KS Different?

At its foundation, the Core i9-12900KS is identical to the Core i9-12900K. It has 16 cores (eight Performance-cores and eight Efficient-cores) and support for 24 threads. The chip has a 150W base power and 30MB of shared Intel Smart Cache. The 12900KS’ clock frequencies are different, however. The complete breakdown is as follows...

CPU Specifications	Core i9-12900K	Core i9-12900KS
Total Cores	16	16
# of Performance-cores	8	8
# of Efficient-cores	8	8
Total Threads	24	24
Max Turbo Frequency	5.2GHz	5.5GHz
Intel Thermal Velocity Boost Frequency	-	5.5GHz
Intel Turbo Boost Max Technology 3.0 Frequency	5.2GHz	5.3GHz
Performance-core Max Turbo Frequency	5.1GHz	5.2GHz
Efficient-core Max Turbo Frequency	3.9GHz	4GHz
Performance-core Base Frequency	3.2GHz	3.4GHz
Efficient-core Base Frequency	2.4GHz	2.5GHz
Intel Smart Cache	30MB	30MB
Total L2 Cache	14MB	14MB
Processor Base Power	125W	125W
Maximum Turbo Power	241W	241W

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In addition to having higher clocks across the board, the Core i9-12900KS also offers a 5.5GHz max turbo frequency when leveraging Intel Thermal Velocity Boost, which allows for higher multi-core turbo frequencies when there is thermal headroom available. Other than those clocks though, there isn’t anything to differentiate the Core i9-12900K and 12900KS. They are both unlocked K-SKUS, and they both offer official support for up to DDR5 4800MT/s or DDR4 3200MT/s memory speeds (or much higher with overclocking), PCIe Gen 5.0 and 4.0, work in the same platforms / socket, etc.

Intel Core i9-12900KS In Retail Packaging

CPU-Z doesn’t reveal any surprises here. The Core i9-12900KS is based on the same stepping and revision as other 12th Gen Core i9 processors. The L1, L2, and L3 cache configuration is also the same. Again, the only real differences are related to frequency. Here, you can see the Core i9-12900K loaded with a single-thread (left), and multi-threaded (right). When thermally saturated, as was the case in this test, clocks will typically hover at the P-cores' max turbo frequency (5.2GHz), though it will boost higher, power and thermals permitting.

We’ll determine what the means for performance next...