SLi Only Graphics Glitch

[Jazzatola]

I was playing HL2 for a while last night and afterwards opened up the nVida control panel to change a few settings. I'm running two eVGA 7900GTX cards but I noticed that in the control panel SLi mode was switched off. I don't remember turning it off myself so I just switched it back on.

Then, when I started up HL2 again, there was a terrible flashing purple hue to the graphics. I tried WoW which was the same. I switched Sli off and it was all good, switched it back on and it was flashing purple again.

First of all, I updated my drivers but that didn't change anything. Next, I figured that maybe one of the two cards was having problems so I tested each of them in turn. I tried each card in each PCIe slot and connected the monitor to each DVI port. Individually both cards were fine in all configurations and there were no glitches to be seen in HL2.

Does anyone have an idea what could be causing this?

 

[mpilchfamily]

Seams like you have ruled out everything but a problem with the motherboard. What motherboard do you have?

 

[Jazzatola]

I'm glad you mentioned the motherboard.

I built the machine last year with an Asus A8N32-SLI Deluxe and was running with SLi with no problems. Then, earlier this year, I managed to fry my bios and ended up getting a replacement board. I installed the replacement but had problems with the SATA configuration. The board would only detect the two drives I was using when they were connected to certain SATA ports. It was a workable solution but in the back of my mind I've always thought that there was a fundamental problem with the board. I suppose this issue with the gfx cards just confirms it.

 

[rbV5]

I've experienced HL2 missing textures NUMEROUS times after changing graphic settings without restarting the game. Perhaps its a similar issue. The purple is the default substitute for missing textures.

 

[Jazzatola]

Hmm, it happened in WoW as well and was not cured by a reboot so I'm pretty sure its hardware related.