I overclock pc's alot your problem is either faulty card or the thermal paste between the gpu and its he's sink has dried out or gotten old, your gpu sounds like its going into safety shutdown, if it's not that the could be the CPU thermal paste has went bad, something is shutting down your PC to keep from messing something up, or there is a bad driver somewhere it don't have to be graphics card drivers could just be sound or lan most likely its thermal paste though happens alot on mine