I thought I'd get one of these instead of a reference HD 5870 card after reading lots of comments and reviews such as the Bit-Tech one about how quiet and effective the Vapor-X cooler was supposed to be. The card works well apart from one problem - the idle fan speed won't go lower than 1455 RPM which is 22% duty cycle. At this speed the Vapor-X cooler is quite noisy. It's far noisier than my previous Nvidia GTX260 card with the stock cooler (which had the minimum duty cycle lowered to 30% 1,000 RPM approx through Rivatuner). Interestingly, the HD 5870 Vapor-X is about 1cm shorter than the Nvidia GTX260 card. It fit in my (modified) Antec Solo case easily without needing any more metal cutting away from the drive bays.
The fan speed doesn't need to be anywhere need 1455 RPM at idle. The idle HD 5870 GPU temperature is an impressive 22c (room temperature 13c approx).
None of the tuning programs that I've tried (MSI Afterburner, Rivatuner, ATI Catalyst Control Centre) will get the HD 5870 Vapor-X idle fan speed any lower. The duty cycle figure will change to a lower number in GPU-Z but the actual fan speed doesn't change. You can manually increase the fan speed above 1455 RPM however, showing that the fan controller can be controlled through software.
Sapphire HD 5870 Vapor-X idle temperatures and fan speed
Editing the graphics card BIOS doesn't appear to have any effect either. The picture below is of the default fan settings for this card as shown in Radeon BIOS Editor. I've tried flashing it with a lower duty cycle setting and also using the lookup table without any success. The fan speed and displayed duty cycle in GPU-Z remain unchanged.
Sapphire HD 5870 Vapor-X BIOS fan settings
Could anyone suggest how I can get the idle fan speed lower than 1455 RPM through BIOS or software settings please.
If I can't make it run lower then the fan looks fairly standard so I'm thinking about a fan swap for a quieter model.