Question : Problem: Video Cards are dying when I launch a game.

I built a new system last week.
Two BFG 8800 GTs (BFG Tech BFGE88512GTOCE GeForce 8800GT 512MB 256-bit GDDR3 PCI Express 2.0)
EVGA board EVGA 132-CK-NF78-A1 LGA 775 NVIDIA nForce 780i SLI ATX Intel Motherboard Thermaltake W0131RU ATX12V / EPS12V 850W Power Supply
4 gbOCZ RAM, and a Seagate 750gb HDD.

I put it together with no snags.

It posted, installed windows, rebooted several times installing drivers, and got out onto the internet.

I looked at some pictures to check out the resolution of the display, and everything was working fine for about an hour.

So I ran Call Of Duty 4 on the default settings to check out performance. I got to the menu, through the opening video, started  the game, and about 3 seconds in (once it had to start rendering graphics for the game), I heard a pop and saw smoke come off of the capacitor on the card right near the 6-pin power connector of my first 8800 (the one my display was connected to.

The system goes down and I smell ozone.

So I took out the card, put the secondary card in the main slot, and checked the connectors. Everything is as it should be. Turn it on to confirm POST. POSTs fine, and I kill it before boot. The power is in the right place, the power supply is SLI certified, I was grounded during installation.

So I set up the RMA for the 8800 while I called BFG and ask them if they think it would be indicative of a card failure. The tech on the line said that she was almost positive it would have been the card, because it was working fine until the GPU had to work.

So I boot up on the other video card, non-SLI, to show the wife the display when she gets home. I pull up pictures, and surf around a little on the net. Then we cross our fingers. I fired up COD4. It went  through all the movies, I started a new game, and the same thing happened.

So I didn't know what to do. I was guessing it was the power supply. My wife thought it was the motherboard. A friend with the same setup thought that it actually *was* the video cards. The S/Ns on the cards were 5 digits apart in sequence. We thought that if they were the same batch that they could have the  same problems.

I didn't RMA the power supply, because I was told by several professional and amateur enthusiasts that if there were a problem with the power supply, that it would be universal, and that it should have never even POSTed if the power supply was the issue.

After consulting nVidia and other forums, it was pretty much unanimously agreed that it would be voltage regulation on the motherboard. The fact that it happened in the same PCI slot was indicative of that.

I replaced the motherboard and both video cards via RMA with Newegg. They arrived today. I hooked everything up, and the same thing as above happened. It booted, and worked just fine for several minutes. When the game started having to render graphics, it died again.

The motherboard from EVGA has a serial number sticker over an old serial number sticker. I can see through it partially, and the last two digits (all that I can make out) are different than that of the sticker that is posted over it. It *could* be the problem, still, but I find that highly unlikely.

How exactly do the cards contact the power supply? Could it overpower the video cards to the point of them frying? It was the capacitor directly next to the PCI-E 6-pin power connector on the card that blew.

The components that remained the same were the RAM, CPU, HDD, and DVD-RW drive.

I'm thinking I may need to now RMA the power supply and the one failed card. While I *did* have them in the SLI configuration today, trying for the second time (an oversight on my part) I don't think that there is a problem with the secondary card. From what I understand about SLI, the first card in the configuration does all the work, and the second picks up the slack. That could explain why it happened with the same PCI slot, and why it wouldn't be a motherboard failure.

I do not have any known good parts to try, as this is a completely new system, and a large upgrade for me.

Why is the failure only when I attempt to run a game?

Answer : Problem: Video Cards are dying when I launch a game.

>Do video cards typically draw less power when not under load, and then attempt to draw more when they need to work?

Yes, playing a 3D game will cause the card to draw more power, as a GPU is similar to a CPU in many respects (nVidia's Tesla is an example of a GPU being used as a CPU).  The more tasks you give the GPU, the more current it will draw.  I have verified this with a Kill-A-Watt device when running a 3D game.

You may be able to swap out the power supply with another one and test with just one card.  COD4 is playable on a single 8800GT, and this will narrow down where the problem is.  I haven't heard many reports where the motherboard caused video problems, but there are plenty where a bad power supply caused it.