The Core i5-9600K should bring a smile to the faces of PC gamers. It's a fantastic way to offset the cost of NVIDIA's latest GeForce RTX graphics cards, which are relatively pricey, by choosing this processor over the pricier Core i7-9700K, or even the i9-9900K, but more on that later. Intel is right in its calculation that the Ryzen 5 2600X can be tackled by moderately increasing clock speeds over the i5-8600K without tinkering with the core configuration. The new i5-9600K is consistently faster than the 2600X at gaming, in all resolutions, and stays ahead of it in all single-threaded and most multi-threaded CPU tests.

When it comes to gaming, the i5-9600K is a "look no further" option for those who mainly game on their PC and don't use the same machine for making money (i.e., productivity that can leverage high multi-threaded processors). Across all our game resolutions, the i5-9600K stays ahead of all AMD processors in our bench, and more importantly, performs within 1–2% of the significantly pricier Core i7-9700K. At our most "academic" resolution, 720p, which highlights CPU bottlenecks in a gaming PC, the mighty i9-9900K ends up just 2.6% faster than the i5-9600K. This lead is narrowed to around 1.6% in 1080p and 1440p resolutions, and a paltry 0.4% at 4K UHD resolution.

Compared to the Ryzen 5 2600X, the i5-9600K is 15% faster at the CPU-limited 720p resolution, 7% faster at 1080p, 4% faster at 1440p, and within 1.5% at 4K UHD. The AMD chip isn't slower by much at higher resolution, but it's the 720p performance that concerns us. Sure, you'll probably never game at 720p, but numbers obtained at that resolution highlight the minimum FPS the machine is capable of in a scenario where the GPU is not a bottleneck.

When it comes to CPU performance, we see an interesting clash between the philosophies behind Intel's 6-core/6-thread setup and AMD's 6-core/12-thread, with SMT trying to compensate for the lower single-thread IPC of AMD's "Zen+" microarchitecture versus Intel's "Coffee Lake." When averaged across all our CPU tests, the i5-9600K ends up 4% faster than the 2600X, but that only paints half the picture. Intel's average is bolstered by big leads over AMD in tests such as SuperPi and MP3 encoding (single-threaded), and less parallelized rendering and simulation tests such as Euler3D, where the higher IPC and up to 4.60 GHz Turbo Boost frequency benefits the Intel chip greatly. This is the reality of the PC ecosystem though—many applications or tasks are single-threaded or only lightly parallelized.

In predominantly multi-threaded tests, such as video-encoding and data-compression, SMT manages to raise performance of the 2600X above that of the i5-9600K, although a couple of percent are not much. H.264 encoding is an interesting test in which the i5-9600K beats the 2600X, a test in which the Ryzen originally beat the i5-8600K. This highlights the idea behind Intel throwing clock speed around to solve the performance gap with the 2600X. The cheaper Ryzen 5 2600 (non-X) is 11% slower in CPU tests, and around that much slower at gaming. The popular i5-8400 is even slower than the 2600 at CPU workloads, but is faster at gaming.

Overclocking the Core i5-9600K is easy because of its unlocked base-clock multiplier, and we managed an all-core manual overclock of 4.80 GHz, which is a massive 29% overclock compared to the nominal 3.70 GHz clock speed of this processor, although just 200 MHz faster than the maximum Turbo Boost frequency of 4.60 GHz. We made a point of testing this manually overclocked chip across all our tests, highlighted by the blue bars in our graphs. Average performance gained in CPU productivity tasks is around 5%, which approximates this 200 MHz clock increase pretty well. With gaming, however, the performance gains are barely 0.4–0.8% (negligible) compared to a stock chip, which is in line with expectations because games still aren't too parallelized, and leaving the i5-9600K untouched to cope with its factory-set Turbo Boost profiles is the simplest way to go for gaming. It will also save you some power on the side.

Just like other 9th generation Intel processors we tested, there is some throttling to the Core i5-9600K when running purely at stock. The processor is rated at 95 W, but can go well above that, to around 130 W when fully loaded. This means that when a highly parallelized load starts on all cores, the processor will run uncapped for a few seconds, until enough time passes and the processor senses that enough heat has "accumulated" in the heatsink for it to limit heat output to 95 W to stay within TDP limits. This is by design because typical workloads happen in bursts, and maximum performance is yielded by this method without breaking the 95 W TDP limit. For longer intense workloads, this does mean that performance will drop after around a minute because the CPU will only boost high enough to stay within its 95 W long-term TDP limit. If you have sufficient cooling, it's a good idea to increase the Turbo limits to avoid this situation. No need to mess with multipliers or overclocking—the CPU will always be stable after increasing the Turbo limits.

Speaking of power, the Core i5-9600K has roughly the same idle and single-threaded full-system power draw as the 8-core i7-9700K, which shouldn't come as a surprise. What also shouldn't come as a surprise is the 19 W increase in multi-threaded power-draw on the i7-9700K owing to the two additional cores. Since the gaming performance of this chip is right up there with the i7-9700K, the gaming power draw numbers are also the same. When it comes down to energy efficiency (work done versus energy consumed), the Ryzen 5 2600X takes a definitive lead in multi-threaded energy efficiency despite falling behind in single-threaded efficiency due to lower IPC.

Our performance-per-dollar charts see Intel processors take a beating for their relatively higher MSRP pricing made worse by terrible real-world prices in the retail markets due to channel shortages. It is here that the $220 Ryzen 5 2600X makes a killing, offering 22% more bang for the buck than the Core i5-9600K. Adding to the AMD chip's value is its included cooler, something the Core i5 lacks. We are more drawn to the value the i5-9600K offers compared to pricier Intel models such as the i7-9700K and the i9-9900K. You get an impressive 19% higher performance per dollar compared to the i7-9700K, which is a staggering 33% compared to the i9-9900K.

Who should buy the Core i5-9600K? You should if you use your machine to play games and your non-gaming activity is restricted to Office, image editing, web browsing, or even game streaming. The AMD Ryzen 5 2600X doesn't have an edge over this chip in any of those machine roles. If you are an amateur content creator who needs the added CPU muscle for video editing or some other multi-threaded workload, you could spend $20 more on a Ryzen 7 2700 for two more cores and many more threads. The Ryzen 7 2700X continues to offer good value for multi-threaded CPU workloads even though in the end, it's bested by the i7-9700K, the most exciting processor to buy in our opinion. The i9-9900K is great if money isn't tight and you want a turnkey solution that's equally good at gaming and productivity. If your main focus is productivity, with highly-threaded apps slowing down your money-making process, you could explore HEDT options such as the Threadripper 2920X. The best gaming CPU from Intel continues to be the humble Core i5. A more budget-oriented option is without a doubt the AMD Ryzen 2600, which offers 47% better price/performance than the 9600K while being "close enough" in most games, saving you over $100 in the process—and it comes with a heatsink, too.