It seems Intel's upcoming Kaby Lake processors will continue the tradition of using thermal compound rather than solder or liquid metal under the integrated heatspreader. Over at the Anandtech forums, users "Chrisch" and "RichUK" have popped the tops on purported samples of Intel's Core i7-7700K processors to apply aftermarket thermal compound with great success. Chrisch achieved 5 GHz with his popped chip, while RichUK got 5.3 GHz out of his. That's a pretty nice step up from the chip's rumored 4.2 GHz base and 4.5 GHz Turbo speeds. After delidding their CPUs, both RichUK and Chrisch saw drops in max core temperature on the order of 25° C, too. RichUK says that after a pass of Intel Burn Test at 5.1 GHz with a 1.376V core voltage, his core temperature never exceeded 72° C.
Previous reports of overclocking the Core i7-7700K—a CPU that has still not actually been released—were a little underwhelming. Most sites that have gotten their hands on samples have come back with relatively meager results and scorching temperatures. Tom's Hardware hit a wall at 4.8 GHz, while Bit-tech.net got a better sample and managed to hit 5.1 GHz. Bit-tech's testers reported that the CPU core was edging past 90° C at full tilt.
As it happens, the 7700K may be subject to the same air-gap lottery that some enthusiasts have observed in Intel's unsoldered desktop processors since Ivy Bridge. On the older chips, those folks have found that temperatures can vary wildly from one CPU to the next because of variances in heat transfer between the CPU die and the heatspreader. These variances are caused during assembly. Some speculate that during Intel's final packaging step, it's possible to end up with too much of the glue that holds the heatspreader to the CPU package during final assembly. When that material expands, it can push the heatspreader ever so slightly up off the CPU die. This makes an air gap, and that means less-effective thermal transfer between the CPU die and the heatspreader.
Your newswriter here delidded his Core i7-4790K a while back and saw only a 15° C reduction in peak load temperatures, but the rumored Kaby Lake Core i7-7700K is a more thermally-dense chip, and it may not benefit from the purportedly-upgraded thermal compound of the Devil's Canyon CPUs. Of course, delidding is dangerous stuff without the proper tools. Overclocking like this also takes some high-powered cooling hardware. RichUK is using an NZXT Kraken X62 280-mm all-in-one liquid cooler. For folks looking to get the most out of Intel's rumored i7-7700Ks, extreme measures like these may be necessary.