This is one of the most hard to track down problems Ive ever had to deal with, I had a freinds PC doing this that literally took me days to try to figure out. A while back like 2 years ago it did it but was alleviated by changing graphics drivers. I think the underlying issue was there just took time to get worse.
We replaced the cheap Thermaltake PSU with a Seasonic 650 Platinum, that didnt cure the problem, tried different sticks of ram, that didnt fix it, changed bios settings, changed drivers, reinstalled Windows, took his graphics card to a family members that was fine, ran it without the gpu, same, tried a different motherboard, did the same thing, tried unplugging everything but the minimum like drives, no change.
I was about ready to pull my hair out.
All in all never really completely pinned it down but what else could it be besides the CPU? (3570k)
Bringing the OC and voltage way down would alleviate the problem until one day a couple weeks ago he called me to say the computer wouldnt boot, tried everything to get it to boot, my freind ended up saying lets just rebuild and he upgraded to a 9600k with Maximus XI Hero, everything has been fine since.
I guess the only thing left to do is drop my family members 2500k in his board and see if it boots again then we will know for sure.
One thing I found interesting when rebuilding was the Thermalright Le Grand Macho comes with a plastic insert spacer that goes around the pcb of the cpu that is specifically for LGA 1151 socket, this is what they say,
"After seeing the photos and reports of Skylake PCB deformation on internet, Thermalright decided to address the issue. It appears the LGA1151 may have some potential problems dealing with the mounting pressure and / or weight of heavier aftermarket coolers (over 500g as specified in intel LGA1150 socket Application Guide). In our endeavour for excellence Thermalright is trying to lower the possibility of this happening by developing a spacer to fill the open area between the load plate and PCB to hold it tightly in place. The spacer fits onto CPU with a 0.5mm raised surface around the IHS fitting snugly on CPU PCB when load plate is latched down."
The 9600k doesnt have room for this spacer, one thing I noticed is that one day during my diagnosis when I pressed down on the Hyper 212 the computer immediately shut down was this coincidence? Maybe these cpu's that aren't soldered the IHS is digging into the substrate or pressing on the core too hard, I dont know.