Recently [H]ard|OCP popped the lid off of an i7-7700k to see if the rumours that once again Intel did not use high quality thermal interface material underneath the heatspreader.  The experiment was a success in one way, the temperatures dropped 25.28%, from 91C to 68C. However the performance did not change much, they still could not reach a stable 5GHz overclock.  They did not let that initial failure discourage them and spent some more time with their enhanced Kaby Lake processor to find scenarios in which they could reach or pass the 5GHz mark. They met with success when they reduced the RAM frequency to 2666MHz, by disabling Hyperthreading they could reach 5GHz with 3600MHz RAM but only when they increased the VCore did they manage to break 5GHz. 

Of course you must exercise caution when tweaking to this level, a higher VCore will certainly reduce the lifespan of your chip and delidding can have a disastrous outcome even if done carefully.  If you are interested in trying this, The Tech Report has a link to a 3D printed tool to help you in your endeavours.

"Last week we shared our overclocking results with our retail purchased Core i7-7700K Kaby Lake processor. We then took the Integrated Heat Spreader off, replaced the Thermal Interface Material and tried again for 5GHz with 3600MHz memory and failed. This time, less RAM MHz and more core voltage!"

Here are some more Processor articles from around the web:

Processors