If you're running the Factory Preinstall then that is a corrupt bloated-out install which no tech enthusiast would run in the first place. Get the superior Clean Reinstall - Factory OEM Windows 7,
but in addition make your Recovery disks first so you can wipe the HD using Diskpart Clean Command
first since code in the boot sector can cause this.
Follow the steps in Reinstall tutorial closely pertaining to drivers
which are automated in Windows 7. Watch closely to see if the problem persists throughout all stages of wipe and reinstall.
If you do all of this then you've elminated software as the cause.
This can also be a Power Supply issue so to start troubleshooting the hardware you can try another PSU to see.