Well, that did not take long. An overclocker has taken a Core i7-8700K processor and cranked it all the way up to 7.405GHz using a healthy dose of liquid nitrogen cooling. While obviously not practical outside of chasing records, the impressive overclock effectively doubled the chips stock clockspeed.
At stock, the 6-core/12-thread Core i7-8700K has a base clockspeed of 3.7GHz, and max Turbo frequency of 4.7GHz. HWBOT user Kovan Yang blew way past both speed limits, hitting the record frequency (for now) for a Core i7-8700K CPU. Previously the record for this same processor sat at 7.3GHz, achieved by der8auer.
To hit 7.4GHz, Yang set the chip's multiplier at 73x and goosed the bus speed to 101.44MHz. There is no mention of how much voltage he had to use, and we're fairly confident it was quite a bit higher than 0V reported in CPU-Z. This was achieved in an MSI Z370 Godlike Gaming motherboard.
In our own hands-on testing with the Core i7-8700K, senior editor Jarred Walton was able to hit a stable 4.8GHz on all six cores with very little effort, albeit temps rose to above 90C. That's partly a result of Intel continuing to use a less desirable thermal interface material (TIM) instead of solder. When adding an extra 0.05V and pushing the chip to 4.9GHz, temps would hit 100C and start to throttle.
Realistically, most users should be able to hit around 4.8GHz to 5GHz, depending on their setup, expertise, and luck of the draw. But rip off the integrated heatspreader (IHS) as Yang presumably did and drown the chip in LN2 (the photo above is not actually from Yang's setup), and the sky is apparently the limit.