Freezes while starting Steam games, unknown cause

Core i7 3820
ASUS Sabertooth X79 Motherboard
16gb Samsung 30nm RAM
2x Diamond AMD HD 7970s in XF
2x Samsung 830 256gb SSDs
Seasonic X 1050 PSU
Custom Liquid Cooling loop
Windows 7 Ultimate x64

Lately I have been crashing every time I start up a steam game, specifically Metro: LL, Borderlands 2, and Bioshock Infinite. This was not always the case. I could easily play several hours uninterrupted but now I'll crash immediately at the startup menu and freeze. I've tried to look at event viewer and windbg, and in the beginning, everything pointed to both a file called "atidxx32.dll" and corrupted memory. After reinstalling Catalyst, though, I continue to hard freeze, but I don't get an event correlated to the game which I was playing before the crash. These freezes are sometimes only ended by physically restarting my machine, but other times I can stop it if I hit CTRL+ALT+DEL quickly enough. Even when I manage to prevent a freeze, no event appears regarding the game. I've done everything I could to try to stop the problem, yet it persists and I am now at a dead end. I have:

Running Windows Diagnostics tool; yields nothing (lol)
Updated Windows
Revoked overclocks on CPU (5.0ghz to stock), GPU (1300core 1600mem to stock), and memory (2000 10-10-10-27-1 to stock)
Reinstalled Catalyst drivers (have tried 13.5 beta, 13.6 beta, 13.3, and 13.2)
Reinstalled Steam
Reinstalled Chipset Driver
Reinstalled Audio Driver
Reinstalled USB Driver
Reinstalled SATA Controller Driver
Reinstalled Marvell SATA Controller Driver
Ran Windows Memory Diagnostics; no errors
Ran CCleaner Registry fixer
Check for viruses with both Malwarebytes and MSE, both of which are up-to-date
Stress tested the system with Linxx and Intel Burn Test, along with 6 hours of prime 95
Tried disabling several combinations of two 'High Definition Audio Devices' and a Realtek Audio Device
Tried reinstalling WINDOWS

Nothing. NOTHING works. HELP. PLEASE PLEASE PLEASE.

Anything and everything available upon request.

Does this issue happen with non-steam based games? Have you checked to see?

Something you might want to try is running your cards in single mode. That is, just running one card at a time to see if one of your cards are failing.

A quick search found this thread atidxx32.dll - Battl - Forums - Battlelog / Battlefield 3
which points that atidxx32.dll may not be getting updated by ati driver installer.

The OP says that by downgrading the video driver to a obsolete version you can 'trick' windows update into updating that .dll for you from Microsoft.

You can then update catalyst to latest version.
Good luck !