About 24 hours, which is enough for 15 mins at each of the FFT Sizes it calculates (8k-4096k). Beyond this for stability testing is pointless because you are repeating exactly the same tests and if it passes an FFT the first time, it will pass it again the second run.
For the distributed compute project Prime95 is actually for, people run it non-stop.
Intel Core i9 9820X @ 4.5Ghz (1.253v NO AVX OFFSET)
ASUS X299 TUF Mark 2
2 x ASUS 2080Ti TURBO (Blower, NON-A)
32GB Corsair Vengeance LPX 3000Mhz (4 x 8GB)
1TB Samsung 970 EVO PLUS NVMe SSD
Corsair HX1200 1200W
Corsair H150i Pro (Corsair ML120's push/pull)
Fractal Design Define S Windowed
Windows 10 Pro
Acer Predator XB271HU 165Hz GSYNC 1440P
Corsair K70 MXRed
Razer Deathadder Elite
Schiit 2Uber Stack + Beyerdynamic DT1770
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