Wait. A 1.1 box? Doesn't the 1.1 have an auxillary fan over the GPU? Would the GPU fan control fall under the same management as the main (rear) fan?

Also, depending on your bios, you could use XBTool to edit and increase the fan speed (though this is a little noisier, but its a non-intrusive "hum" sound that's really not that bad since I play games decently loud anyway). I've upped my fan speed to 60% (from the default 20%) and my system stays at a tolerable 48 degrees Celsius even after 2-3 hour stints. Without the sped up fan, my sytem was reaching temps of about 54 degrees C.

Additionally, I think most people here will attest to making sure the system is in a well ventilated area and the vents were unobstructed. It really does make a world of difference.