Well, he did say he's running Windows 8, which I don't think ninja-updates like Windows 10 does. If he meant Windows 10 then yeah, I'll put my money on a ninja-update porking the drivers, requiring a DDU/reinstall fix.

OP, did you really mean Windows 8? First step is to blow out your drivers and reinstall the latest one. Pull all but one of your cards off the board. If one comes up, keep adding them until you're either done or it doesn't work. That at least starts narrowing it down.

That all cards suddenly just went away is almost universally an OS/driver/software problem.