ran memtest for about 2 hours came up with nothing so restarted,, took the disk out and got blue screened it restarted got to windows 7 loading screen and bsod'd me again this happened a couple of times so i pulled all the usb devices out which are always plugged in game controller , external HDD ... restarted went into uefi didnt change anything then restarted it.. it said launch start up repair i chose not to and it booted normally after,,, any ideas what could cause this