Graphics Card Sleep Mode?

I recently bought a XFX Radeon HD5750. I am a very light sleeper so I used to have a laptop to torrent for me overnight as it was extremely quiet. I sold my laptop and bought this desktop that has fans in the PSU, GPU, CPU, and 2 case fans. The loudest by far is the Radeon HD5750. I can control the fan speed with the Catalyst controller but I don't want to damage anything by turning it way down.

I don't need any graphics as it downloads, hell the monitor is off. Is there anyway I can 'hibernate' it somehow but still be downloading? Thanks.

Oh I am running Windows 7 64-bit.