So, I broke the golden freakin' rule of, "if it ain't broke, don't fuck with it."

I flashed the BIOS on my ASUS 2GB 6950 to a 6950 (as per this article), and it went flawlessly. I was jacked up.

Rebooted again just to double check everything; all good. GPU was idlinge @ around 58-61 degrees C, just a few degrees higher than normal.

1. Fired up some BF3, joined an empty server, started flying a chopper while watching my temps.
   

2. GPU temp is climbing towards 80 degrees C, I'm starting to worry a bit.

3. Game gets choppy, crashes.

4. I get back to my desktop, and the whole thing shuts down. Fucking great.

So I give it a sec, and power her back on. Turns on, board LEDs & fans turn on, drives spin up, GPU fan spins up. That's all the good news.

Monitors show nothing, no beep codes (gotta check on my PC speaker though), and the power button won't respond -- only way to power down the system is the switch on the back.

USB keyboard and mouse don't illuminate, though keyboard's USB port is supplying pass-though power). That's it.

Things I've tried:

EDIT: Attached a buzzer to JFP2, NO BEEP CODES.

Clear CMOS (battery removal & JBAT jumper)

Two GPUs - 8800GTS in BOTH PCIE slots, and an OLD PCI GeForce FX 5200 (hah!)

1 DIMM (nope)

Moving the BIOS jumper on my GPU to the other position (closest to the Crossfire connector) & rebooting

Full system specs:

• AMD Phenom II X6 1100T Black Edition

• 8GB GSkill Ripjaws Series DDR3 1600

• COOLER MASTER ATCS 840

• Thermaltake Frio

• ASUS EAH6950/2DI2S/2GD5 Radeon HD 6950 2GB

• MSI 870A-G54

• CORSAIR Professional Series HX750 (750W)

I'm thinking it's either 1) something stupid I'm overlooking, or 2) somehow I fried my GPU, mobo, PSU or all 3 of 'em together. If that's possible.

Also, this is NOT a new build - system has been up and running for about a year with no issues.

EDIT: Attached a brand new PSU (Themaltake 850W) -- NO JOY. With --or without-- one of my 3 video cards, no post, no beep codes, no nothing. I've pulled the RAM, tried one stick in a buncha slots, unplugged everything from the mobo (inside and out) ... I'm out of ideas. There a lot of folks on the MSI forums with the same or similar issues.

So screw it, I'm going to buy a new motherboard. If I'm lucky I can find a brick-and-mortar store here in CT tomorrow. Thanks for the help.