Not all motherboards support that option unfortunately, especially changing the case fan speeds. Many of them support changing the CPU fan speed, but it will do no good when the GPU is overheating, because the cpu fan is just sucking in the hot air and blowing it out into the case. And the GPU fan cannot be controlled from the bios (I'm not sure about integrated cards though).

Reborn,
I followed your advice through the video you made. One thing I noticed is that there was no change in the sound coming from the case after I increased the GPU fan speed, and I also noticed the slider would automatically go back down to 35% after I upped it. I couldn't stop it from coming back down. Perhaps my card is not capable of doing that (although I don't see why that would be the case). It would stick if I set it to less than 35%, but not if I set it any higher. Interestingly enough, after doing this (whether it worked or not), I have been able to play the game at 1280 x 960 without any crashes. Granted I've only played for an hour at a time max.

I know this fix didn't work perfectly because my system will still crash when I try to play SC2 if I don't set an external fan to blow on the case. That game is probably at the max of what my card can support, though.

I've been able to solve the problem temporarily by keeping a fan blowing on the open case when I play CSS and SC2. However, in the last few weeks I've noticed 2 things:

1) Something in the case is vibrating and making a very loud rattle (probably a fan...maybe even the GPU fan)
2) My system will occasionally crash even when I'm not playing a game, just doing something else slightly less graphics intensive.

Anymore I keep a fan blowing on the case anytime the system is on. I'm pretty sure my GPU fan is dead or going out. Thus I'm pretty sure I need to get a new video card. I've had my system for about 2.5 years now and don't really have the money to spring for a brand new one, so I'm looking to put in a new video card that is similar to, or just slightly better than, the one I currently have. Does anyone have any suggestions as to cards that might fit that description? I've used GeForce cards in multiple systems and been generally satisfied, so I'd like to stay with the brand. It'd be great if I could find something for less than $150, and I definitely don't want to put the currently-top-of-the-line card in.

Didn't read everyting in this thread, but:
Since you have nVidia get this: http://www.nvidia.com/object/nvidia_sys ... _6.06.html. You need only NVIDIA System Monitor - it'll allow you to monitor both GPU and CPU temperature. Check if any of those are overheating.
If you're sure that VGA's fan is dead (or dying), instead of buying new one you can just replace fan&heatsing. I also have 9600 GT and this one http://www.newegg.com/Product/Product.a ... 6835887021 keeps it cool and quite. (more you can look at: http://www.newegg.com/Product/ProductLi ... der=RATING)

I'm pretty sure the GPU is overheating. I've been monitoring the temperature using the NVIDIA System Monitor (thanks for the suggestion, carrot). The magic number seems to be between 135 - 150 C. The GPU is almost always over 100 C if I'm running any graphics intensive software without having the fan on it, but the fan does wonders for cooling it down. Finally yesterday I walk in after leaving the computer alone for a few hours and it says it's near 230 C! I put the fan on it and it rapidly cools down towards 100 C. Then I turn the fan off and watch it crawl back up into the 130s. Then the temp suddenly drops to zero and about 10 seconds later the system crashes.

you should look at replacing the fan ASAP then, and you may need to replace your card fully. If you're temperature reaches as high as you say it can do bad things to the GPU itself, sometimes melting aspects of it. Spend a few bucks replace the fan then see where it goes from there. If theres core damage you'll find out later on. My GPU doesnt' hit over 100 unless its dusty, barely even hits 80 most days.

Just get a new card. http://www.compusa.com/applications/Sea ... No=6976278

Thanks for all of the advice, guys. I decided to go with a new video card and got a GeForce GT 440 1 GB card. With the mail-in rebate it will only cost me about $71 including tax, S&H.