I have two XFX 7600gt XXX's in SLI on an Asus A8N-SLI (Base model) Motherboard. I have been using this setup for probably six months, with excellent results, low 6100's in 3dmark 06, and no problems whatsoever.
Then, about a week ago, while playing a graphically taxing racing simulator, a bunch of bright blue splotches began flashing on my screen. They are not like typical artifacts...which look like bright various colored outlines around certain contours in the graphics...no its not like that at all...these are large areas of the screen covered in bright blue flashing patterns, or sometimes just horizontal bars flashing down the screen. I tried reinstalling two of the most recent Nvidia driver releases (84.xx and 93.xx), and the problem persisted. I tried checking each video card individually, by setting the mobo to single card mode, and starting up the machine with only one card installed. Both cards performed flawlessly, both getting very consistent high 3500's in 3dmark06, without any blue splotches. so now i am left wondering if there is maybe a problem with my nforce chipset, or the bridge connector that connects my two cards. or maybe there is something else on the mobo that could be causing this. anyways, all i am really confident in at this point is that both 7600gt's are functioning properly. Oh, and in case anyone is thinks any other components could be coming into play here, I have an Ultra Xconnect 550W SLI Rated P.S., an AMD X2 3800+ running at 2.5 ghz and 1.4v, 2048mb Corsair XMS pc3200 running at 416 mhz 2.5-3-3-6, two 320g seagate HD's, a Zalman CPU cooler, and three 120mm case fans on a controller. All overclocks on CPU and RAM have been set at that level and running completely stable for many months. Thanks in advance for any input.
Also, I wanted to add, that once the problem started while playing the racing simulator, it has continued every time I have tried to play any of my other games (Oblivion, BF2 & 2142, COH, T.W. 06, etc. etc.) or tried to run 3dmark. It is not intermittent. But when I go back to just one card (either card) all of the games play just fine (albeit considerably slower than when SLI was working )
While it is possible that you may have a hardware fault, IMHO it is unlikely, most components fail when they are new or old, not usually after a few months.
I have had driver problems that I have been unable to resolve without the reinstallation of windows from scratch, alot of driver removal programs do not remove all references to the previous versions etc.
I personally would reinstall windows and install a known version of the driver that works or even try the newest version and see if that does the job.
This is odd to happen out of the blue. I see that everything works correctly with just one video card. Have you tried further testing by using each card by itself in each PIC-E slot? You can rule out the SLI bridge by removing it then try running SLI. Often enough SLI still works without the bridge (in the case of the 7600GT) just not as effective. Have you tried another four pin molex connector to the "EZ" power plug on your motherboard? It might be a good idea to test these cards in another system if at all possible. If you continue to have problems please let us know and start a support ticket if you have not already done so at www.xfxforce.com.
Thank you for your concern and suggestions, I am planning on starting a help ticket at XFX when and if i determine that it is a problem with one of the cards, but at this point i dont think it is. I will do further testing as you suggest, and let you know. It is kinda second priority to full time job, part time school, and closing a home mortgage though, so be patient...