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First off, I'm a sysadmin, but I'm pretty removed from home computers and gaming machines. A friend of mine asked me to look at an issue on his machine where it was hard locking sometimes, or there were artifacts all over the screen. He is/was running dual Nvidia 8800GT cards in SLI. I'm unfamiliar with how SLI works, but I would think that it would work with only a single card. The machine doesn't get to a login screen with both cards installed, it will usually lock during the Vista splash. Out of the 2 cards, one of them causes all kinds off issues on its own, so I'm pretty sure its no good. However, when using the other card by itself, the device manager says that the device isn't started. In the Nvidia control panel, there is no SLI or Physx options to turn off SLI, which I would expect, as there aren't 2 cards physically installed.. Is the error in device manager to be expected because the second card isn't present, and windows is expecting SLI?

Things that have been done:

-Latest BIOS on computer

-All chipset drivers updated

-Latest drivers from Nvidia

-Tried each card one at a time.

What is the possibility that both cards are bad?

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up vote 1 down vote accepted

SLI (Scan-Line Interleave Scalable Link Interface) is a method for linking two (or more) video cards together to produce a single output. SLI therefore only works when you have two (or more) graphics cards running.

You will only get SLI options displayed in the nVidia control panel if you have both graphics cards installed and running correctly under Windows. Go to Windows device manager and look under Display adapters, there should be two separate nVidia GeForce 8800 GT cards listed. If one of the cards is malfunctioning you may find only one card listed or both listed but one card with a yellow exclamation indicator next to it.

From what you describe it would appear one of the graphics cards is malfunctioning. You could either replace the card or simply run the PC off the one working graphics card.

Update: The error in device manager isn't to be expected if a second card is not present.

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It isn't a laptop, and the options are limited in device manager because the device cannot start. – Dan Aug 12 '10 at 19:01
It's called Scalable Link Interface on nVidia cards now. Still it's good to see someone who remembers Voodoo cards and 3dfx. – AndrejaKo Aug 13 '10 at 10:57
@AndrejaKo Thanks for the correction, I'll update my answer. – Chris Driver Aug 13 '10 at 14:03

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