I have an ISGC 300 CPU cooler. According to the specifications its fan speed ranges from 800 to 1300. I am using Open Hardware Monitor to monitor the fan speed. I have an ep43t motherboard with the F4 BIOS. According to the motherboard manual if I disable the smart fan control (SFC hereafter), then the fan works on max speed. If I enable it, then I can set to auto, PWM or voltage. If the fan has 4 pins, then PWM is the right choice, and if the has 3 pins, then voltage is the right choice. When I change the CPU fan settings in BIOS I have the following results:

  • by SFC enabled and set to voltage it reaches at most 400 RPM
  • by SFC disabled I have 850 RPM
  • by SFC auto I have 810 RPM

I have a manual control device, with it I can set the fan speeds between 250 RPM and 730 RPM. Is there a way to reach the 1300 RPM somehow? Why can't I reach it?

Note that I constantly have CPU temperature issues, since the fan works only on 800 RPM...


According to the specification the fan uses 12V. Is there a way to measure the voltage it gets? I have a voltmeter...

I found that the fan cable has a male "2 pin molex connector" near to the 3 pin female. I am not sure what that is for.

  • Even on 800RPM your heat issues should not be that bad. If you can only achieve acceptable temps with a full-load cooler, than something else is wrong. Check cool paste and airflow. May 31, 2017 at 14:16
  • @BramVanroy There were several issues, I had to mod the BIOS for Xeon CPU, the Tjmax was 85°C instead of 100°C when I measured the temperature, I applied cooling paste on the CPU and the mobo bidges, and other stuff I don't even remember. I fixed them and I sold the computer months ago...
    – inf3rno
    May 31, 2017 at 18:40

1 Answer 1


There is supposed to be a speed control connected to the two pin connector. Perhaps you forgot to attach it. If you can't find it, shorting those two pins should lock it at maximum speed (I think).

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  • I got a speed control, but it connects to the 3 pin - beetween the motherboard and the fan - instead of the 2 pin... I can reach with it only 730 RPM. Is the 2 pin always for controls, is it possible that shorting it damages the PC?
    – inf3rno
    Nov 9, 2016 at 20:47
  • @inf3rno Are you sure you hooked up the speed control correctly? It should set the full range of speeds. Nov 9, 2016 at 21:16
  • The problem is not with the speed control. I removed it, since I don't want manual speed control, and put a jumper on the 2 pin. Now I have more than full speed 1440 RPM. Thanks! :-)
    – inf3rno
    Nov 9, 2016 at 21:21

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