Fan speed problems

First of all, I'd like to thank you all for being such a valuable resource, though this is my first time posting here, I've used this website countless times for help with other issues.

Alright, now the problem I'm having is with my fans on my Biostar P4M900-M4 motherboard. It has two fan headers, both with three pins. I've connected two coolermaster fans scavenged from an old computer to those headers. All fans are 3 pin fans. The problem I'm having is that they always run at full speed no matter what! The CPU temp according to the bios is about 20 celcius, but the CPU fan runs at approx 4,500RPM and the case fan runs at 2,000RPM constantly.

I've talked to biostar support, and I've been told that I should buy a 4 pin fans (to put on my 3 pin headers?) in order to regulate the speeds correctly. This makes no sense to me, as I cannot see why a PWM fan would be needed if the PWM control wire wouldn't even be connected.

If someone can shed some light on this problem, or case and CPU fan standards in general, it would be greatly appreciated.

Thanks in advance for your help!
10 answers Last reply
More about speed problems
  1. Hi B

    I took a peek at your bios setup and its a little on the primitive side, no means for controlling the fan speeds. Try SpeedFan:
  2. Sorry, I forgot to mention that I tried speedfan already... I configured it properly (I think) and automatically controlling the speeds didn't work, and manually changing them didn't either. Thanks though.
  3. Hmm... Some of those DIY controllers looked pretty interesting, since I dont have any empty 3.5" or 5.25" bays empty, I might go with one of the cheaper ones if I can't solve the problem, thanks for that link. On the other hand, I'd like to figure out what is causing this problem though.

    The motherboard says it has a "fan speed controller" so wouldn't it make since that it should be able to regulate the speed of the fan by changing the voltage supplied to it? All my other systems with 3pin fans have been able to adjust speed accordingly.

  4. Does anyone have any other suggestions to fix the problem? Would buying a 4 pin fan to put on the 3 pin connector like biostar tech support said be worth trying? or just a waste?
  5. I already have two 3 pin fans, both coolermasters, that should be able to work with my motherboard, but they always run at max. All 3 pin fans have the same speed control features right?
  6. There is nothing fancy about a speed fan controller all it does is raise and lower the voltage to the fan. Link me to your fans and do your CoolerMaster have one of these (or something similar):
  7. I'm afraid I can't really link to them... they were just plain black fans that came with an old computer. There's a coolermaster sticker on the fans, but no model numbers or anything like that.

    I'm thinking that they should work just fine, and that the board might be messed up, but I thought I'd ask before I spend some money to follow biostar's wierd support advice.
  8. I have an old CoolerMaster fan with a speed fan controller on my NB, found it in one of my boxes still don't know where it came from. Good luck.
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