White flashing bar on solid black screen after start up

[Drugpickle]

A few weeks ago, I moved my perfectly functional desktop to the basement for a couple days. After bringing it back up and booting it up, it went directly from the "press f12 to x" menu, to a black screen with nothing except a white bar flashing in the top left. There's no LCD error message on the motherboard, and it seems to be a problem with the HDD after doing some research. I've tried unplugging the HDD, as that's the only suggestion I could find, but it's still doing the same thing.

 

[Drugpickle]

tried changing boot order in BIOS settings, still didn't help

 

[Vic 40]

Does a clear cmos help?
Does it start from a boot cd/usb stick? if you have one,windows/ubuntu/hirens boot cd ...