i have a heating issue with gpu and can't change fan speed

[jdh440]

my 8600gt gets up to 89c.i can't change the fan speed because it goes back down to 30% when i start a game about 5 to 10 minutes in i think it causes low fps in my games. could it be my power supply that's causing this? is it not giving enough power to my system?
I'd like to turn the fan setting higher to cool it better, thanks

here's my specs:

Pentium 4 3.0ghz

1.5gb ram 2x 256 and 2x 512

8600gt 256mb

160gb 7200.rpm hard drive

DVD burner 24x

350w power supply

 

[blackhawk1928]

You have a perfect power supply for it. That shouldn't be the problem. Your card is definatly overheating, i will tell you that. Which software are you using for fan speed control??? If aren't already using this program, use RivaTuner, I use it and is a very good programming. Also ntune is a good program for fan control. make sure you have a well ventilated case and open it up if it helps.