Need some advice on some odd computer crashes

I've got a computer that's maybe six months old, if that, using a single ASUS GeForce 580 GTX direct CU II video card and now it crashes either to a reboot or just a straight black screen with the last sound repeating over and over or a general growl from the speakers. I downloaded new drivers from nVidia a couple of months, when Skyrim was giving me some general crashes but I was still able to get 4 hours in at a stretch.
These crashes only ever happen when I'm playing a game with 3D models in it (Audiosurf, Beat Hazard, and Bejeweled 3 don't ever crash it) but the time to each crash isn't always consistent. I thought it could be my video card overheating but the inconsistencies in time makes me think maybe that's not it, and both fans appear to be running fine.

As an example here are the times I've gotten recently:
Skyrim = 5-10 minutes (although fog and haze seem to have always affected it)
Portal 2 = 1 hour last week and 5 minutes the last time I played
Bionic Commando Rearmed = 10 minutes
and finally:
Batman Arkham City = 1 hour 30 minutes (before I got bored and kicked it into the benchmark program)
The Arkham City benchmarker ran all the way through to the end but then I couldn't exit out of it. It gave me an option to hit esc to exit but that didn't respond, but the snow kept falling over the city.

I figured if anything would get the card to crash the system right away it would be Arkham City, because the graphic settings are as high as they will go and PhysX settings are only one notch below full , and all of that processing is hitting the 580 GTX I don't have any secondary PhysX processor setup and, with exception of BC:R, the other games don't use PhysX. Could this just be a driver issue or do you guys think my video card is just overheating?

Why are you blaming your videocard in the first place? Did you test the system with another card(or onboard video if you board has that?)

It might still be a heat issue with your main board or cpu. Have you checked the temperatures?
Also it might be a problem of your main board chipset when there is a high amount of data on your bus. A firmware update could help with that.

Also I agree with Mace, try testing another viceo card if available, that might help to find the problem.

I talked with my brother today, he works in IT, and he figures it's a heat issue as well. I just figured that if my video card was overheating, or something else was over heating, the games would be crashing at a similar rate, even this morning I played LEGO Harry Potter for over an hour without a glitch and then I got bored, and I haven't run into a crash in any other context. Also I never had any major crash issues until I started playing Skyrim, I doubt there's a correlation but there you go.
Anyway, I've got a few ideas to work with now.
By the way, is there a way to check the temperatures of my cards\CPU\etc. without actually opening the case? On my old machine I had a thermostat wired into the system that would tell me how hot the CPU was running but I don't have anything like that in this one.

http://www.cpuid.com/softwares/hwmonitor.html

So will this program keep track of temperatures even after a crash? Because, like I said, the crashes only occur in full screen games using 3D rendered models, and the crashes are unpredictable.

What fun! You can be the one to find out! :>

So has anybody here actually used this program who can tell me.

I've run some virus scans in safe mode and under regular operation and they have come up clean. I checked all of my fans and they're all running properly so cooling shouldn't be an issue, unless all of the parts are badly designed, so what else could this be?
My system only ever crashes when I'm playing a game but it doesn't crash on every game. Starcraft 2, Batman Arkham City, LEGO Harry Potter never crash. But Skyrim always crashes within five minutes and Portal 2 varies.
Does anyone have any ideas what else it could be and how I can test for it?

What brand/model of CPU are you using, and what type of RAM?

Af friend of mine had a similar problem, using an AMD quadcore, turned out it was his memory timings, I figured it out by setting the timers a bit "less tight" manually, and it ran stable. This was permantly resolved by updating the motherboard's BIOS, and one of the fixes applied to the memory timings.

Use Prime95. It's a stress testing software. You will want to set it up so it doesn't test the memory so much. I used it to test my system stability, which turned out I had the wrong memory timings/voltage settings. If your system locks up while its running then it's less likely to be a GPU issue. Use CoreTemp to keep an eye on the CPU temp's.

I am using an AMD Phenom II X6 Black Edition CPU and 16 Gb of Corsair XMS3 RAM. My motherboard is an ASUS M4N98TD EVO AM3 NVIDIA nForce 980a SLI ATX AMD Motherboard.

If I use Prime95 to test my system can it diagnose where a breakdown occurs, especially if the machine reboots? Because, like I said, the crashes only occur during games and any program that tracks the stats of my hardware's behavior is useless if I lose all of that information when the breakdown happens.

No, but it will give you an idea of system stability. If you can run it for 24hrs without it crashing it's considered you have a stable system. You have a similar system as me. IIRC AMD use higher voltages for memory than those defined by the manufacturer. You should look into your voltage settings and timings as other's have previously mentioned. Small increments are the safe way to go. You won't find a quick fix, it took me months to get my system stable.

Well, there you go... First, upgrade your BIOS to the latest revision and see if that helps. If you are afraid to take on this task yourself, ask your brother to assist you in this.

Thanks for the help, I'm going to try implementing some of these in the next couple of days.