I've already exhausted my knowledge on this one, so forgive me if this post is a bit long. I built a computer 6 months ago for my wife and it worked fine until last week. Then it randomly shut down and would lock up while trying to boot on the boot screen. I cleared cmos and it allowed me to do startup recovery, but it "failed to fix the issue" so I reinstalled windows on the HD (moving the old install to windows_old). It worked, so I started installing drivers again, but then when I restarted to finalize installations it locked up again.

This time, I took the hard drive and hooked it up to my computer, backed up all her files, and then formatted the hard drive before reinstalling it. (again had to clear cmos to let me boot from disk) It installed windows, I installed drivers, and it worked for a few hours but then died during startup again.

So, then I got a new HD, cleared cmos, and installed clean again, with the same result as the time before, it worked for a few hours, installed windows updates, then crashed on the 3rd or 4th time turning it on.

I decided next to try reinstalling and then going online to see if there were any updates for the BIOS or drivers on the Motherboard, but now I can't get it to even bring up the boot menu, so now I'm just left wondering was it the motherboard, or is it the CPU, or the RAM?

The problem was strangely intermittent so I thought it had to be a software issue, since a hardware issue would ALWAYS fail to boot, right? But now it seems to be a hardware issue, because it's not bringing up anything. Any suggestions?

System:

Windows 7 64-bit

970A-DS3 Gigabyte Motherboard

AMD Phenom II X4 955 Deneb 3.2GHz Quad core Proc

GeForce GT 430 (Fermi) 1GB Video Card

500W PSU

2 x G.SKILL Ripjaws X Series 4GB 240-Pin DDR3 1600 RAM