The Intel Core i9-9900KS Special Edition Review: 5.0 GHz on All the Cores, All the Time

Intel's Core i9-9900K sits atop the desktop PC gaming throne with leading performance in a wide range of games, allowing Intel to dominate the sliver of the ultra-high-end processor market where it remains uncontested in raw performance by AMD's competing Ryzen 3000 processors. That earns is a spot on our list of Best CPUs. 

Intel designed its new Core i9-9900KS Special Edition to take things one step further by taking the best silicon from its -9900K manufacturing line to create a new halo part specifically for gamers and streamers that boosts to 5.0 GHz on all cores. Surprisingly, Intel only assigns a $513-$524 recommended price for the chips, which is a relatively slim $25 premium over the standard -9900K models. 

Given the blistering-fast performance we found in our tests, that pricing would equate to a wonderful deal if you could find the chip at recommended levels, but we fully expect retailers to take advantage of the limited availability (the KS is only available until the end of the year) and charge a premium. 

For enthusiasts and gamers that don't want to deal with the hassles of overclocking, or for extreme overclockers looking for that last drop of performance, the Core i9-9900KS is unquestionably the new leader in gaming performance at both stock and overclocked settings. The gaming performance delta between the -9900KS and competing chips is often substantial enough that gaming enthusiasts looking for the absolute most performance, regardless of price, will seek out the processor. 

AMD isn't sitting 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. That chip isn't as fast at gaming as the Core i9-9900KS, but it does bring competitive gaming performance and much more threaded horsepower. 

Intel Core i9-9900KS Special Edition Specifications

In short, the Core i9-9900KS is identical in nearly every fashion to the Core i9-9900K. The KS features the same 14nm++ process and Coffee Lake architecture as the standard Core i9-9900K, so it sports the same feature set, like dual-channel DDR4-2666 memory support and UHD 620 graphics. 

The -9900KS drops into existing 300-series motherboards after a BIOS update, but 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 beefy power circuitry.

Higher clock speeds are the Core i9-9900KS's real attraction. The -9900KS's premium silicon supports a 4 GHz base clock, which is a 400 MHz improvement over the -9900K that leads to a beastly 127W TDP rating. That's a big increase over the Core i9-9900K's 95W TDP. 

The -9900KS also delivers a 5 GHz Turbo Boost across all of its cores under any workload (AVX included), while the standard -9900K only boosts to 5 GHz on two cores. As expected of a higher-binned processor, Intel's Core i9-9900KS should overclock higher than garden-variety -9900K chips, but the silicon lottery still applies (your mileage may vary). The higher quality silicon also affords tremendous power consumption advantages, which we'll cover shortly. 

Like the Core i9-9900K before it, the -9900KS comes with Intel's translucent plastic dodecahedron packaging, doesn't come with a bundled cooler, and features solder TIM (sTIM) to facilitate efficient thermal transfer from the die to the heatspreader. That helps with overclocking, which is fully enabled through the -9900KS's unlocked ratio multiplier. 

Like all ninth-gen chips, the -9900KS supports Intel's free and simple-to-use Performance Optimizer (IPM) software tool that automatically tunes and overclocks your processor. As with all of Intel's processors, overclocking voids your warranty unless you purchase a separate Performance Tuning Protection Plan that covers damage due to overclocking. 

Surprisingly, Intel's standard warranty only covers the Core i9-9900KS for one year, which stands in contrast to the standard three-year warranty period for the company's other desktop processors. Intel chalks this shorter warranty period up to 'limited availability,' but its 40th-anniversary Core i7-8086K also sold in limited quantities and carried a three-year warranty. Intel is transparent about the shorter warranty period, but you should take it into account. 

Core i9-9900KS Boost Frequency and Thermals - 5 GHz, all the Time

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We turned the same amount of attention to the KS's 5.0 GHz boost as we have with our series of AMD Ryzen 3000 boost clock tests. We put the chip through the wringer in a variety of workloads with different cooling solutions and found that, given adequate cooling, the chip sustains 5.0 GHz on all cores at stock settings, regardless of instruction type (AVX workloads included). 

As outlined in the charts above, we stress-tested the chip with both a beefy custom watercooling loop with two 360mm radiators, and a Corsair H115i AIO watercooler. Both cooling solutions facilitated a consistent 5.024 GHz clock rate, but air cooling doesn't seem to be a viable option. We paired the chip with a beefy Noctua NH-D15S air cooler, and at stock settings, the chip often bumped against its 100C thermal limit, which triggered clock throttling to protect the processor. Contrary to some reports, the Core i9-9900KS will obviously not support overclocking with an air cooler.

Intel's official spec sheet lists a 130W cooler as the entry-level solution. That fits well with the Core i9-9900KS's 127W TDP, but Intel defines the TDP at base frequencies (PL1 - Power Level 1), and that value represents the amount of power the chip dissipates under load, not actual power consumption.

However, Intel's chips shift into Power Level 2 (PL2) during boost activity, which the company defines as 25% over TDP (158.7 Watts for the KS) for a boost duration (Tau) of 28 seconds. Motherboard vendors often ignore boost duration limits, as we see with our own tests above, so you can expect very aggressive boost activity with most motherboards. Performance will vary based upon each motherboard vendors' policy, but the parameters are configurable. Even with Solder TIM, thermal density presents challenges. If you plan on tuning, open- or closed-loop liquid cooling is a must. Even then, the thermal output could limit your overclock

Core i9-9900KS Special Edition Binning

Every processor die is unique, even when harvested from the same wafer. Intel tests the individual dies from each wafer in a binning process to find the best and worst silicon, first sorting out die with defects for use in models that have fewer cores or deactivated graphics units. In some cases, dies are discarded altogether.

Even after the initial sorting, some die can deliver higher frequencies at a lower voltage than others, while most die require more voltage (which generates more heat) to deliver the same level of performance. Intel assigns each tier of chips into separate bins that dictate if the chip will find its way into downstream models that have lower frequency requirements, or if the chip will be reserved for high-end models, like the Core i9-9900K.

But like all chip manufacturers, even Intel's fully-functional halo parts have some wiggle room in the specifications to account for silicon variation, meaning the chips are programmed for the lowest common denominator of the bin. That leaves some chips that fall on the high end of the binning bell curve, or "thin bin" parts in Intel parlance, that find their way into the hands of lucky owners who win the silicon lottery.

Intel's Core i9-9900KS represents the cream of its silicon crop. Intel says these rare chips offer what we would typically expect from an overclocked system, but at stock settings. Let's see how that looks throughout our test suite.

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