I bought a AMD / ATI HIS HD 7870 to replace my old HD 4870.

I noticed that the fan speed does not scale with the temperature: The fan speed does not get below 28% (read from catalyst / automatic fan speed)

If I manually change it in the catalyst to 20% then it has the same speed than 28% : about 900-1000 rpm.

With HIS iTurbo i manually can change the fan speed below 20%. But I noticed that changing the fan speed below 16% results in 3200 rpm.

This is really stupid and annoying since my PC is a ultra silent PC and all fans are running with about 500 rpm when the PC is idle (windows / musik movies, etc.)

Is there any way to change the fan speed to a reasonable speed like 500 rpm by software or hardware adapters (I really don't like to put a poti between the 12V line)


Lowest fan speed physical constraint, not a software limitation. Very low frequencies may couple with power supply or generate electrical signal noise.

  • How is it physical - since the software controls the PWM signal? Any ideas how to modify the fanspeed below 1000 rpm? – Thorsten Niehues Dec 4 '12 at 8:22
  • I though about a resistor (poti) on the 12V line - but that's only the last option. Or may be a modified BIOS from "TechPowerUp Radeon Bios Editor" when they support the HD 7000 series – Thorsten Niehues Dec 4 '12 at 8:25

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