Can't change fan speed on my asus 9600 gt please help

I have an Asus EN9600GT/TOP graphics card with the glaciator fansink and it runs way too hot. It idles at about 46c and can hit 80c when overclocked playing crysis. I am not sure if 80c is acceptable or not, but I have noticed a considerable decrease in performance when it goes over 70. From everything I have read, I believe that the fan is set at a very low speed. I want to set it to run at 90-100% but I can't change the fan speed with Ntune or Rivatuner. The options are grayed out. I have downloaded NIBITor V4.6 but I am unsure how to use it. I try to use the utility to detect my card's bios but it doesn't work and I have no idea how to access my card's bios. All I want to do is change the fan speed I will do all of my overclocking with software. By the way I have great airflow in my case (3 80mm fans, and I don't care about the noise the fan will make.

This is a pre-built Acer Aspire that i purchased before I knew how to build my own.
Nforce 630i/gforce 7100
E2220 2.4ghz pentium dual core no OC (PRE-BUILT COMPUTERS SUCK)
Asus EN9600GT/TOP video card OC'd to 755 core,1897 shader,2100 memory
Antec true power trio 550w ps with a total output of 36A
Vista home premium 32bit