Back when the 2nd nations cup was happening, I started getting this error - TF2 would cause my PC to heat up to insane amounts of heat and it would shut down after approx. 20 minutes of playing. I turned down my setting to the lowest and opened my PC case for better air circulation. And it stopped.

A couple of months later it started happening again, so I set up a household fan to blow at my PC to cool it off. And it stopped again.

And now it started doing it again. Even when my fan is up, my case is open, my computer is clean, my settings are set to an abominally low level, it eats up 80-100% of my CPU(according to the CPU meter gadget) and causes it to overheat after less than 15 minutes of play, EVEN THOUGH THE INSIDE OF THE PC ISN'T HOT!

I could really use some help, because I don't want to give up TF2 forever

P.S.: It also overheats when I don't have the fan on when playing some games that have much better graphics than TF2, e.g. Borderlands on nearly max graphics.

P.P.S.: my specs: AMD Athlon 64 X2 Dual core 4.8GHz
Geforce 8500 NT
4GB ram
Windows 7 64 bit
DirectX 11
The PC is 2,5 years old.

TF2 will always eat up as many cpu cycles as it can get. The game is very cpu limited, if your framerate goes above 60fps regularly (I doubt it with your setup) you could enable vsync which would allow the cpu to idle.

It sounds like a poorly mounted cpu heatsink to me.. is the fan working on the cpu heatsink.. is the heatsink warm to the touch?

The fan is working and the heatsink is a few degrees above room temperature.

Actually what temperature is the CPU reporting?

I initially read this as your cpu was overheating but it could be a graphics card or a chipset cooling issue (if you are overclocking, see below).

Also what CPU are you using, are you really overclocking an X2 to 4.8ghz or are you adding up each cores clock speed to get that figure?

Yeah, I pretty much suck with computers, so I don't even know how to overclock

Here's a screenie of what SpeedFan shows while the PC is pretty much idle(torrent, steam and antivirus working):

Well, there's something wrong with the GPU temperature too.

I've got a notebook (so only a small fan), Zalman NC2000 cooling pad, Flash Builder open up and my GPU temperature is only 56°C (Although it is underclocked when not using too much resources, but still, 72°C is the max I had even when playing Crysis or WoW).

Check to see if the graphics card fan is spinning. It could also be blocked with fluff depending upon the type of cooler used on that graphics card.

i use HW monitor and compare the temps with riva and speedfan. i prefer it but alot prefer speedfan, iv have them all running at the same time and occasionally i get totally different readings also a screeny of your cpu-z would be good to see how your overclocking. first port of call should be to clean out all your heatsynks (gpu included)

I don't believe he is overclocking. He added the clock speed for each core together, which is meaningless.

oh.. ok