Overclocking

We didn't doubt that we'd hit a decent frequency with the Core i5-8600K, although it's worth pointing out that this was a retail sample. This hopefully gives a little more of a realistic indication of how most perform than an engineering sample.

We started at 1.3V and aimed for 5GHz as this was easily attainable on our press sample Core i7-8700K, however even 1.31V and 1.32V weren't enough for stability at 5GHz. In the end, we settled on 1.34V, and while this is relatively high, the temperatures were hovering around the 80°C mark under full load using an all-in-one liquid cooler, which is absolutely fine.

Performance Analysis

If one thing was clear in the results overall it's that the Core i5-8600K didn't have everything its own way. While it beat both Ryzen 5 hexa-core CPUs when overclocked by a sizeable margin in HandBrake, the Ryzen 7 1700, which also costs a bit less than the Intel CPU,  was even faster, and the same was true in the PC Mark 10 photo editing test, Terragen 4, and Cinebench. The latter favoured AMD, and here even the Ryzen 5 1600 was faster than the Intel CPU both at stock speed and when overclocked.

Where Intel still has dominance is in games ,and Deus Ex is one example where Intel is much faster, with the Core i5-8600K noticeably quicker than any AMD CPU. Ashes of the Singularity was less clear-cut, as the Ryzen 7 CPUs were snapping at its heels at stock speed, but the massive overclock we applied saw it edge out a lead after some tweaking, and doing the same for the AMD CPUs didn't yield enough of a boost to keep up. As per usual, in more GPU-limited games such as Fallout 4, there's very little difference across the field as well as between stock and overclocked speeds.

Conclusion

The Core i5-7600K lost its place as the dominant all-round CPU to AMD, which offered far superior multi-threaded performance for the same money, albeit with a hit in some games. The Core i5-8600K's two additional cores do a lot to improve the situation, but with AMD's recent price cuts, it's a long way from offering better value than the Ryzen 5 hexa-core CPUs given they now cost around £100 less. It now has competition from AMD's eight-core Ryzen 7s too, with the 1700 and 1700X now retailing for under £300, which means that while Intel is again faster in some games, elsewhere AMD is better value for money.

If you're building a purely gaming rig, then Intel is still the better option all other things aside. As soon as you delve into content creation or other multi-threaded, multi-tasking scenarios, AMD is not just better value but is actually often faster too. It's little wonder, then, that we can probably expect octa-core mainstream CPUs from Intel in 2018 if you believe the rumours, but really, Intel needs to look at its pricing compared to AMD, especially in the wake of price cuts throughout November and December. 

The Core i5-8600K is still a potent CPU that's a good all-rounder with a much needed boost to multi-threaded performance compared to the Core i5-7600K, however it hasn't dealt a knockout blow to AMD - it would have to be around £50 cheaper to match the Ryzen 5 hexa-cores on value, and we can't help wonder whether Intel will need to include Hyper-Threading at this price point in future too given that the Core i5-8600K is now competing with the likes of the Ryzen 7 1700 and 1700X in terms of cost.