This is a post for a friend as i'm all out of ideas.

He is currently running:

i7 6700k - Stock
As rock z170 fatality itx gaming
Corsair hydro 100iv2

His temps are averaging 80c on stock under load. This seems quite high to me? Since he hasn't attempted to overclock yet. No load they're around 22-27c.

I have got an i5 so i cannot compare mine to his, but this seems crazy high to me. My i5 is OC to 4.7 at 1.375v and getting 20c lower temps, albeit i have a custom loop.

Any ideas?

Thanks.

Under which program is he getting such high temps?

I would first check theres no overclocking software messing with his voltages, check the voltage is staying stock under load.

I would check the pump is running ok, i dunno if ya get pump speed read out on them coolers or if its just on/off but im sure youll feel it vibrating when its on.

Check the CPU and cooler are getting good contact, clean off both surfaces and replace the paste, it can get dust in when your fitting it preventing good contact.

I only get 75 or so with stock settings on an Asrock Extreme 4, with a NH-U14S with AVX on prime, gaming will see me 60-65 with quite a warm case

Sounds a bit on the warm side, may be worth seeing what the voltage is being reported.

1.26v on my vcore usually.