Striker II Extreme, BFG 8800 GTX x2 SLI problem

System Specifications
ASUS Striker II Extreme, NVIDIA nForce® 790i Ultra SLI™, BIOS 0704
Intel Core 2 Quad Q9450 2.66GHz 12MB Cache
BFG GeForce 8800 GTX OC2 x2, NVIDIA ForceWare 175.16
Corsair Twin3X 2GB DDR3 TWIN3X2048-1333C9DHX PC3-10600 (4GB total)
Corsair HX 1000W Modular Power Supply
Windows XP Professional 32-bit, SP3


I'm running x2 BFG GeForce 8800 GTX OC2 in SLI, both in the blue PCI Express slots, exactly how it's supposed to be setup as detailed in the motherboard manual. The problem ONLY occurs when SLI is enabled and doesn't persist when SLI is not enabled.

The problem is that the system freezes when I play video files usually after about 10-20 seconds, no sound, no mouse or keyboard input, however the picture is still present, yet frozen. This occurs even when the video is minimized, I have to hard restart the computer to resolve it. This also happens in games, but the system freezes after a longer period of time, roughly 30 minutes or so (I've only tested wow for this).

I've tested the graphics cards individually, so it seems both cards are working fine. I've also tested multiple SLI bridges to no avail. I've updated the display drivers, motherboard BIOS, motherboard chipset etc. to the latest versions, reinstalled Windows several times and changed numerous options in the NVIDIA Control Panel and system BIOS. The problem was occurring on the previous motherboard BIOS (0508) and the previous display driver (169.96).

The one thing I noticed was that in System Information in the NVIDIA Control Panel the video BIOS is different on the two cards, one is 60.80.0e.00.15, the other is 60.80.0e.00.05. It seems the second card's BIOS is 60.80.0e.00.05 and the IRQ is stated as 0, whereas on the first card the IRQ is stated 16. However in Device Manager the IRQ on both cards is stated as 16.

I haven't overclocked at all and have the BIOS settings set at default.

Here are the voltages as displayed in the BIOS

Vcore voltage: 1.28v
CPU PLL voltage: 1.150v
CPU PPL voltage: 1.10v
Memory voltage: 1.61v
NB Core voltage: 1.31v
SB Core voltage: 1.47v
DDR3 Termination voltage: 0.80v
3.3v: 3.26v
5v: 4.96v
12v: 12.09v


Any help or suggestions would be greatly appreciated.