Overclocking too far causes instability.
Overclocking your ram too far or tightening timings too far can cause instability.
Instability in the ram can cause OS corruption, program corruption, etc.
Memtest tests the ram before it gets to the os meaning that nothing can be corrupted.
To run prime you need to load ur os
Ah yes! Durr *slaps forehead* Thank you for that. Well, like I said, I have no available floppies and I don't have a CD burner on this computer. My brother is asleep so I can't get to his computer. His powerbar is taken away right now anyway.