How fast will Core i7-4790K go in the hands of a respected system integrator? It's fair to say that we weren't overly enamoured by the Intel Devil's Canyon processors. The two Haswell Refresh chips, Core i5-4690K and Core i7-4790K, were launched last month with heightened frequencies but didn't, at first glance, live up to their promise in terms of overclocking headroom.

Cast your memory back to our initial analysis and you'll recall that Intel uses a 'next generation polymer thermal interface material' (NGPTIM) between die and heatspreader that's said to enable cooler and higher-performing parts. This, combined with extra on-chip capacitors for smoother power delivery, should in theory make the 22nm chips more willing than earlier Haswell processors when it comes to high-end overclocking.

That wasn't necessarily the case with our first review samples, as both the Core i5 and Core i7 parts struggled to run stable when pushed beyond 4.4GHz. Not a great return by any means, and disappointing for enthusiasts who were hoping to see speeds in excess of 5GHz with simple air cooling.