7700k trips bios cpu overheat protection

[Laptop4079]

I'm having trouble admitting defeat. I've searched on multiple different forums to no avail. I recently delidded my cpu to open up more thermal headroom and started overclocking again. I made it all the way to 5.2ghz at 1.4v stable no problem so I bumped it up to 5.3 with no voltage changes reboot and as soon as it posts I get a "cpu overheat protection press F1 to enter setup" I'm having a hard time believing this because under full load it doesn't hit 80c. I tried to get it to boot by disabling thermal monitoring in the bios but it makes it to the windows 10 welcome screen before it locks up. I can't find anyone with this same problem, I've been overclocking a while and I've never seen a cpu crash like this. bios issue maybe? I'm stumped...

mobo: asus maximus viii hero latest bios 3703

[Silent_Scone]

The fact you've delidded the CPU points towards poor contact between the die and heat spreader. You've probably already surmised this, though. Make sure to check for contact with the CPU cooler as well, but sounds likely you'll need to re-lid the CPU once again.

[Menthol]

The top binned 7700K from Silicon Lottery was 5.2 @ 1.450 volts, I clocked mine at 5.4 @ 1.456 volts using a water chiller
I don't know how many chips Silicon Lottery binned but it is more than most people could possibly test so it's pretty safe to say 5.2 is about all anyone could do without extreme cooling.
If it locks up you probably need more voltage, if it hits thermal protection just booting like Scone says your re-lid may not be perfect and cooling not good enough for anything above 5.2 Ghz even if the chip is capable
You have reached the top binned speed for 7700K already my friend, anything above that requires $$$$ in cooling and a very good chip.

Disabling protections in the bios is not recommended and a sure fire way to kill your chip, I say that from personal experience