Intel proved that even without HyperThreading (HTT), 8 cores make for a faster processor than the i7-8700K (6-core/12-thread). Both chips have similar clock speeds and architecture, but the i7-9700K has a 200 MHz higher boost clock. The lack of HTT is a boon rather than a bane as the processor has fewer PPCs than the i7-8700K, and hence, its boost-clock application headroom is spread across just 8 PPCs instead of 12. This translates to better sustainability of clock speeds north of 4.50 GHz, and approaching 4.90 GHz. Gamers couldn't have asked for a better scenario.
Across the 720p and 1080p gaming tests, the Core i7-9700K ends up faster than even the Core i9-9900K for the reason I explained above. The lead is rather slim at around 1–2 percent, but it's there. Even in GPU-limited resolutions such as 1440p and 4K UHD, the i7-9700K ends up a tiny bit faster, but the differences are insignificant. Games that are heavily multi-threaded, such as "Civilization VI", still show the i7-9700K ahead. It is hence safe to conclude that the i7-9700K—not the Core i9-9900K—is the fastest gaming processor. You can go ahead and pair this chip with the fastest graphics cards in the market without worrying about CPU bottlenecks. However, the fact that this is the fastest gaming processor only paints half the picture.
If you set aside gaming, the Core i7-9700K is still a mighty capable processor for creativity and productivity tasks. It is around 5% faster than the Ryzen 7 2700X and i7-8700K, which also means there is little to no reason to upgrade from either. Lack of HTT and 33% lesser L3 cache only translates to 13.8% less performance than the i9-9900K. The differences vary wildly between applications, though. For low-threaded apps, only clock speed matters; here, both processors are very similar, with the 9900K having the edge due to its 100 MHz higher boost. For multi-threaded software, it comes down to how well a given software benefits from HyperThreading as some only improve by 10% in performance despite twice the logical core count; others gain well above 50% from the same change. Compared to AMD's 2700X, the same things matter: IPC and clock frequency make the Intel CPU a winner for single-threaded tasks, while the Ryzen 2700X beats the Intel processor, sometimes by quite a bit, when highly scalable multi-threaded apps are used. Overall, the 2700X ends up 5.2% slower across the non-gaming half of our test suite.
While the i7-9700K and i9-9900K are no doubt the fastest processors for gaming out there, they're not significantly faster than some of the options that let you save a lot of money. We haven't had a chance to test the i5-9600K, but the previous-generation i5-8600K is just 5.5% slower than the i7-9700K at 720p, 4.5% slower at 1080p, 2.5% slower at 1440p, and practically indistinguishably so at 4K. If you can live with such slim performance gaps, you can end up saving at least $120, which you can invest elsewhere, such as in a bigger SSD or an effectively "free" 240 mm AIO liquid CPU cooler.
The Ryzen 7 2700X is the closest AMD option to this in terms of platform and pricing. It's between 2.5 to 4.4 percent slower than the i7-9700K at 1440p and 4K UHD gaming; however, the gap widens to 7.2% at 1080p and 15.9% at 720p. Of course, you won't be gaming at these resolutions, but we tested them to expose a CPU-limited scenario, which means when an even faster GPU is used, the CPU will drag back performance. Testing at 720p is also useful as it clearly determines the maximum FPS you can get with a given CPU no matter how fast the graphics card is.
Intel has finally revamped the heatspreader on all new Coffee Lake processors, which now uses solder instead of thermal paste, resulting in better heat transfer. This matters for overclocking because previously, the CPU temperature would shoot up quickly when overclocked with higher voltage, limiting the maximum clocks. Thermal performance of the Core i7-9700K is clearly better than the 8700K as temperatures change much more gradually than before. Our manual overclocking on air netted us 5.0 GHz on all cores, which was limited by heat. With a 240 mm all-in-one watercooler on the CPU, 5.1 GHz was no problem; 5.2 GHz was almost stable, and heat was never an issue.
Overclocking, while easy because of the unlocked multiplier, is made slightly complicated by the 95 W TDP limit of the 9700K, which will automatically drop clocks when it senses too much power draw. For example, when set to 5 GHz all-core with some extra voltage, clocks will instantly drop to around 4 GHz as soon as you put a serious multi-core load on the CPU. To raise this limit, you'll have to adjust the power limit in BIOS or XTU—a first for Intel, it is no problem as long as you are aware of it.
The same power-capping mechanism also limits the CPU's boost clocks, even when running completely at stock. Since the processor is specified to respect a 95 W TDP limit out of the box, highly threaded, demanding apps will run into this 95 W limit quickly, and boost clocks will drop to stay within the 95 W power envelope. This means that even when you choose not to overclock your processor at all, increasing the "Turbo TDP Limit" beyond 95 W, in line with what your motherboard VRM and cooler can handle, will instantly result in higher performance for these applications. In our testing with Blender rendering, we gained 10% performance just by upping the TDP limit, without any manual overclocking. It seems the sweet spot for TDP adjustment is around 140 W, so plan your cooling accordingly if you want to go down this road.
Overall, Intel has managed to refresh its portfolio around the $350-$400 market with the Core i7-9700K. There's enough in this chip to warrant choosing it over the i7-8700K, and if you're gaming, you need to look no further than this chip. If you're a gamer and aren't starstruck with the Core i9 brand, the Core i7-9700K is a nice way to save $150 by not opting for the i9-9900K. You could save some serious cash by opting for Core i5 chips that are less than 10% behind. The Ryzen 7 2700X isn't much slower either, but is significantly cheaper at $320, and has added value thanks to its included cooling solution and cheaper motherboards.
At the time of writing, Intel CPU pricing is whack, and the Core i7-9700K is priced north of $420, which further erodes its value. Your decision to buy the i7-9700K should hence be purely predicated on whether you were originally looking to buy the pricier i9-9900K and whether you're mostly gaming on your rig. If the answer to both is yes, then pick the i7-9700K and party with the savings.
I'm seriously considering the Core i7-9700K for our next VGA testing rig instead of the Core i9-9900K.