Overclocking

We managed 5.1GHz with our Core i7-9700K and 5GHz with our Core i9-9900K, so anything around those marks would be a good result for the Core i5-9600K based on this experience with these Coffee Lake refresh CPUs. 

We hit 5GHz fairly easily sitting at 1.3V vcore, and 5.1GHz was achievable too without crazy hot temperatures. In fact, it seemed to run 5-10°C cooler than our Core i5-8600K at similar speeds - reasonably less toasty but maybe not quite what you'd expect from the switch to solder. In any event, Hyper-Threading and heat do seem to be the Core i9-9900K's Achilles' heel when it comes to overclocking, as both the Core i5 and Core i7 have managed slightly higher clock speeds.

Performance Analysis

We'll start with multi-threaded performance, and as expected the Core i5-9600K offered modest gains over its predecessor with around 30 points added to the Cinebench score and very similar results in PCMark 10 and HandBrake, which were mostly within the margin of error we'd expect. The cheaper Ryzen 5 2600X outperformed it convincingly in HandBrake and even a 5.1GHz all-core overclock couldn't better the AMD CPU, with the similarly-priced Ryzen 7 2700 in a different league.

In games it was unsurprisingly neck and neck with most Intel CPUs hitting the maximum frame rates in Deus Ex, with AMD a little way behind with its Ryzen 7 2700X. Our new test, Far Cry 5, seems to love cores and threads but still favours Intel, so the Core i5-9600K fares reasonably well here, sitting in the middle of the graph above the AMD crowd.

Cinebench's single-thread test revealed a fair amount more poke at stock speed from the Core i5-9600K compared to its predecessor. However, its multi-threaded score of 1,036 pales against the 1,372  achieved by the Ryzen 5 2600X, which costs £50 less. Again, the latter isn't as quick in some game titles and does lack lightly-threaded grunt, but if your PC faces a mix of content creation and gaming, AMD's six-core CPUs still make a very strong argument for themselves.

Conclusion

With a lack of multi-threaded grunt and slim gains over Intel's existing quad-core CPUs in most games, the Core i5-9600K doesn't really find any traction or get us drooling, much like the Core i5-8600K last year. If you have £250 to spend on a CPU, AMD's Ryzen 7 2700 costs just £20 more and offers close to twice the performance in multi-threaded applications once overclocked, while only being a little slower in some games, especially when fast memory is used. 

As a result, Intel's only 9th Gen K-series six-core CPU doesn't really leap out as an attractive proposition, with previous generation Intel quad-cores doing a similar job in most games for less cash and other CPUs offering better value if you'll be throwing some content creation at your PC too.