Intel Core i9-9900K 9th Gen CPU Review: Fastest Gaming Processor Ever

Intel Strikes Back

Although Intel added more cores to its previous-gen Coffee Lake processors in an effort to keep up with AMD's Ryzen CPUs, struggles with its 10nm node obviously delayed a more significant response. The company's ninth-generation Core processors, otherwise known as the Coffee Lake refresh, represent another step forward in a contentious battle for desktop supremacy as the company looks to maintain its top spots on our list of Best CPUs. 

Intel's line-up matches AMD's Ryzen core-for-core, including a new Core i9 with eight Hyper-Threaded cores (8C/16T) and the highest frequencies we've seen in the mainstream space. There's also a bulked-up Core i7 armed with two extra cores, plus a revamped Core i5. AMD isn't setting still though: The company recently released its own new flagship, the 16-core 32-thread Ryzen 9 3950X, to fend off Intel's new challengers.

AMD's high core counts, aggressive prices, and nods to enthusiasts have earned it plenty of goodwill. Now it's Intel's turn to respond. The Core i9-9900K, for instance, ships in a a translucent plastic dodecahedron obviously meant to wow system builders, similar to the way AMD impressed with its Threadripper packaging. Intel also switched back to using Solder Thermal Interface Material (STIM) between the die and heat spreader, facilitating better thermal transfer to cope with more cores and higher overclocks. Ninth-gen Core CPUs are also Intel's first with hardware-based mitigations for the Meltdown and Foreshadow vulnerabilities. These should minimize the performance impact of circumventing recently discovered exploits.

Core i9-9900K is the fastest mainstream desktop processor we've ever tested. But it's also one of the most expensive. Knowing that Intel does not match AMD's value proposition, is the ultimate in desktop performance worth paying extra for? The new Core i9 was incredibly impressive through our benchmark suite. However, most users would be better served by cheaper alternatives, such as Core i7-9700K.

Then again, if money is no object and you have the need for speed, Core i9-9900K is the CPU to buy.

Intel Core i9-9900K

The Coffee Lake refresh begins with three new K-series processors. They all feature the same underlying Coffee Lake microarchitecture as previous-gen models. And as expected, the Core i5 and Core i7 brands are represented. This time around, though, an eight-core, 16-thread Core i9 commands the spotlight.

The new K-series chips are manufactured on Intel's 14nm++ node, include an integrated UHD 630 graphics engine, sport unlocked ratio multipliers that enable easy overclocking, and boast support for dual-channel DDR4-2666 memory. Intel also responds to increasing RAM density by doubling memory capacity support up to 128GB.

Core i9-9900K's Solder TIM improves the thermal transfer efficiency between the die and heat spreader, facilitating the headroom needed for two more physical cores on the Core i9 and i7 models without violating a 95W envelope at base clock rates. What's more, the -9900K's base frequency is 3.6 GHz, just 100 MHz lower than the previous-gen Core i7-8700K. And that's after adding those two extra cores.

The STIM, which is applied inside all three new models, also improves overclockability. Enthusiasts who previously lauded AMD for using Solder TIM in its Ryzen processors should be happy with Intel's decision here.

Improved heat dissipation also facilitates impressive clock rates across the ninth-gen models. Core i9-9900K stretches up to 5.0 GHz when two cores are active, outstripping the Core i7-8086K and its ability to hit 5.0 GHz on one core. As you can see in the chart above, Intel is pushing the voltage/frequency curve with its eight-core models. They both feature much higher boost multipliers than previous-gen CPUs. These should help extend Intel's advantage in lightly-threaded tasks like gaming. Meanwhile, the extra cores help Intel compete readily against Ryzen in more taxing workloads.

Core i7-7820X is perhaps the most comparable CPU from Intel's high-end desktop portfolio. But it employs a fundamentally different design. The $600 chip requires an expensive X299 motherboard, is best paired to a quad-channel memory kit, lacks integrated graphics, and utilizes a mesh architecture for connecting on-die logic instead of the familiar ring bus (check out our deep dive for more information). As we've shown, the mesh architecture has a negative impact on some desktop-class workloads, so it isn't the best solution for enthusiasts.

As expected, the -9900K's extra cores are accompanied by two additional 2MB slices of L3 cache, adding up to 16MB across the processor. The Core i7-9700K comes with the same 12MB of L3 cache as its predecessor. Given a higher core count, though, this actually represents a lower cache-per-core ratio, meaning Intel purposely disabled some of the -9700K's cache for the purpose of segmentation.

Intel's Core i7 series traditionally features Hyper-Threading, allowing one physical core to execute two software threads simultaneously, thus boosting performance. Kaby Lake-based processors included up to four cores and eight threads, while Coffee Lake offered as many as six cores and 12 threads on the highest-end models. The 95W Core i7-9700K breaks this tradition with eight cores and no HT support. If you assume that HT yields a 15-20 percent performance uptick under ideal conditions, then Intel's clever removal of the feature on its $374 Core i7-9700K should make the 8C/8T CPU faster than the 12-threaded Core i7-8700K in most workloads, maintaining the carefully manicured product stack.

Ninth-gen Core i5s still come with six cores and no Hyper-Threading, just like the Coffee Lake generation before them. The 95W Core i5-9600K ($265) operates at a 3.7 GHz base clock rate that boosts as high as 4.6 GHz. Intel pairs each core with a 1.5MB of L3 cache, adding up to 9MB.

The new Core CPUs drop into existing 300-series motherboards after a BIOS update, though Intel's partners also have a slew of Z390 motherboards available, which you can see here. As we'll illustrate, the Core i9-9900K, specifically, draws enough power to make VRM selection an important factor in your motherboard purchase, especially if you plan on overclocking. Luckily, most high-end Z390 motherboards already employ beefier power circuitry than the Z370 models.

Plan on buying a beefy cooler for the Core i9-9900K, too. Its eight-core die hides beneath the same heat spreader used on previous-gen six-core models, meaning that even with Solder TIM, thermal density presents challenges. Intel's official spec sheet lists a 130W cooler as the entry-level solution. If you plan on tuning, open- or closed-loop liquid cooling is a must. Even then, thermal output could be what limits your overclock.

Let's see how the Core i9-9900K and its stablemates perform in our test suite.

Update 10/22: Corrected the recommended pricing for the Ryzen 7 2700X in our efficiency charts. 

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