sounds to me like a short circuit or something. try removing the board from the case and test it bare on a bench with only graphics, a disk and 1 ram connected/plugged.

there are simply too many possibilities on what this could cause, so try them one by one. starting with ram, then storage, then everything else.
i also would air-clean everything when you take your stuff out of the case, especially all slots and connectors.
if all is working fine outside the case, please check if you overtightened some screw on the motherboard or have a cable or debris on the motherboard tray that could shorten stuff.

if nothing of that worked, then you might have a defective board...