Yeah, you still need to do the voltage test. It doesn't matter what the rated wattage of the power supply is - it's the voltage that it actually provides that matters, and that can degrade over time.Thanks for the reply I really appreciate it.
I am indeed planning on doing a dual 690 setup once I get two cards running stable. It may not be practical but I'm more interested in cool hardware than crazy fps. And at only $89 a card for what was once a $1000 videocard that can still hold its own, I find that awesome.
I bought these cards three weeks ago and was constantly getting dpc watchdog violations and black screens. So after I got the dpc violations figured out the next thing I did was try a different power supply.
My original is a Thermaltake 875watt unit. I ended up taking my EVGA 1300watt out of a computer that I have running dual gtx 590's and it didn't seem to make a difference at all.
I am using an EVGA x99 classified board so I decided to plug in the extra power connector that feeds the pci-e ports...but it didn't make a difference.
I cleaned the pci-e slot but still no joy.
It really wasn't until I received the replacement card Monday that I decided to completely rule out any problems with my computer hardware or software, because the new card works perfectly.
I have a volt meter.... somewhere. I'll hunt for it and post my findings.
Failing that, assuming it's not something like the GPU dies overheating (I assume you checked for this already, beyond just replacing the grease), I'd be inclined to suspect a board issue. It could be a cracked solder ball or trace, degraded dies, or something power related. You could conceivably try turning off SLI to see if the problem goes away when you only run one of the GPUs.
Edit: One other thing to check for is missing tiny SMD capacitors. These are super easy to knock off the board via rough handling, particularly when you see a pile of the cards stacked up like some ebay sellers like to show in their photos. As I showed in my thread about the 290X, you can get this kind of behavior if even one of those tiny caps is missing, if it's the right one.