Random Pc crashes

[Ashh55]

Okay so since 3 or 4 months I'm experiencing random black screens, I have tried checking my ram one by one, reinstalled gpu drivers , reinstalled windows. My gpu works fine with no artifacts and is stable on benchmarks. is it a psu issue?

 

my specs:

Hp z400 workstation

Intel Xeon x5660

4 sticks of 2gb OEM memory (8gb total)

Xfx Amd Radeon Rx 560 4gb vram

PSU and Mobo are Hp