I don't know why, but my computer started randomly freezing while I was playing graphics-intensive video games. I immediately believed this to be a graphics card problem, and thus removed the graphics card and used my onboard graphics to try to run my computer. Now it doesn't post half the time, and freezes even when I'm trying to set BIOS settings. I have reset CMOS, replaced the CMOS battery, taken out and reinserted the graphics card, tested my monitor, and none of these have been conclusive.
I currently use
AMD Phenom II X3 720 (unlocked 4th core)
ASUS M4A785TD-V EVO (no USB 3.0/SATA 6GB/s)
4 GB CORSAIR XMS DDR3 1600MHZ
XFX HD4770 512 MB
2x WD Caviar Blue 320 GB HDD, RAID 0
CORSAIR 450W PSU
It's been working fine for more than 6 months. I don't know why this has recently started to happen, I've moved my computer from college dorm back to my house, but I haven't added any new parts, nor have I taken out old ones. Please help.