I am new to the forums, so I am not quire sure is this is the right place to post this thread. If you think there is a more applicable location, please tell me.
Here's my rig:
Intel Core 2 Quad 2.66 GHZ
700 W Raidmax PSU (SLI Certified)
EVGA NVidia nForce 780i SLI
2x GeForce 9600 GT 512 MB in SLI
OCZ SLI-Ready edition 4 GB (2x2GB) DDR2 800
Windows 7 32 bit Professional
Hitachi Deskstar 1 TB 7200 RPM
Seagate Barracuda 320 GB 7200 RPM
I built the system in 2008 and have been having some trouble with crashes and booting. Occasionally the computer will just crash for what seems like an entirely unexplained reason. This usually happens during gaming but not always. After these crashes and upon reboot, the system will fail to load windows 7. It will either simply stop loading at the windows 7 screen, or sometimes before but it always clears the BIOS. Oddly, I have found that the only way to allow the comp to boot past this point is by unplugging the SATA cable to each hard drive and then plugging them back in. I have no idea where this issue is coming from, and could really use a hand trying to pin it down. The Seagate hard drive is pretty old at this point, I purchased it in 2006, so I do not know if is is still up to scruff, but it seems to operate just fine in other respects.
If the BSODs are "fixed" consistently by pulling the SATA cables, I'd start your troubleshooting with your HDDs. Run the S.M.A.R.T. test on each drive. Start with the quick test. If the drives are good enough to pass the quick tests, these test should only take ~2 minutes. After that, run the extended test.
Next on the list, RAM. BSODs are often caused by memory issues, so run MemTest86+ on your RAM. It is better to run MT86+ on your RAM sticks individually. Allow the test to run for about 5-6 passes.
Also worth mentioning are your GPUs. Considering the age of these cards, I wouldn't be surprised to find out that the fans are failing. Make sure you clean the cards thoroughly to avoid overheating. Download GPU-Z. Run it at idle, and run it while gaming. Check the differences in the GPU temps.