My PSU (Super Flower Golden Silent 500w) is at the limit of what I need to power my system (PSU calculator says 480w needed). Recently when using music software under moderate load (20-30% CPU usage) I've experienced random and sudden system restarts, just black screen reboot with no warning. I've only been able to do half a memtest as I didn't know it took so long, however no errors were found. Would the PSU be at fault? I'd assume that a failure would take place when the GPU and CPU were both taxed in gaming, not when doing less demanding tasks.