All I can say is .....
Do NOT use AIDA 64 for stressing as it is not stressful enough.
Use either prime 95 26.6 1344k to 1344k, in place FFTs checked. Also u can use Realchench stress test, 2.44 or 2.56. Version 2.56 is more stressful as it uses (afaik) AVX so it will probably downclock your cpu if you have it set up in the bios(avx offset) so watch out on that.
First test if you can pass 1 hour, then if you are happy test 8 hours.
Anyway....if you pass prime or realbench for 8Hours, you are good to go.
For me for example, i7 4790K, 5100MHz..
.....for realbench 2.44, I need 1.335V for 1 hour.
But for realbench 2.56, I need 1.347v for 1 hour.
You can see the difference(Bear in mind the cpu is always at 5100MHz no matter of AVX).
Prime 95 26.6, 1344k, is similar to realbench 2.44, in terms of "how hard the test is". Temps are also similar.
CPU: Intel i7 4790K 5100MHz @1.335V MB: Asus ROG Maximus VII Formula RAM: 4x4GB Corsair Dominator Platinum 2666MHz CL10 VGA: Asus ROG GTX 1080Ti Strix 2152MHz @1.131V SDD: Samsung 870 PRO 1TB NVME + 860 EVO 1TB PSU: Asus ROG Thor Platinum 850W MON: Asus ROG Swift PG278Q 27"