Reduce Sapphire Toxic Radeon HD4870 Fan Noise
 

The representative from Sapphire recently sent an e-mail with two files attached; ATI WinFlash v2.0.15 utility and BIOS file 85VCTOXI.008. The BIOS file was developed specifically to address complaints about noise with the Toxic Radeon HD4870, and the flash utility provides a simple, Windows-based means of applying it.

http://www.bigbruin.com/2008/toxicbios_1