Try a different monitor.  If no change, try restart the pc and enter bios screen.  Does it persist on basic bios screen?  if no change, remove discrete gpu try integrated gpu. most common causes: bad monitor (change monitor it goes away) video adapter bug (goes away on bios screen) defective video card (stays on bios screen but goes away on integrated gpu)
Tried BIST, it passed (issue could not be replicated).
"DS: Stripes/lines on screen, how to determine the cause?"