Windows, Bios, everthing is up to date. I even removed the bios battery to reset everthing to the default settings… RAM seems go be ok, memtest86 and windows memory diag showed no issues. As i said, when the system is cold start the artifacts are visible even on the short back screen of the video bios or when i boot from usb (for memtest)… at this point, no windows software could be the cause of the issue. Could be a faulty PSU the reason for this (even when the voltage on the 12v rail seems to be normal?)…