HELP...Bios saying that my 8inch case fan is running 1900rpm...

By Deathrattle
Mar 26, 2005
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  1. Hi
    I was looking in my BIOS at "pc health status" and it reports that my CPUfan is running at around 4500rpm yet my big blue case fan (8inch i think) is only running at 1900rpm

    I downloaded "SANDRA" and got a mainboard readout ,and it said that one fan was running too slowly , and also that my mainboard was too hot (55C)
    Yet my bios says my mobo is 33C

    Also could it be that my case fan speed is controlled by the MOBO and its running it slowely because everything is infact relatively cool ?
    Or is my fan broken ?.....its only a few days old

    Is there anyway to turn my fan speed up to make it run at full speed like my cpu fan

    Hope ive explained all this properly , is I confused the hell outta myself writing it :)

    thanks........................................................John
  2. Deathrattle

    Deathrattle Newcomer, in training Topic Starter Posts: 20

    or maybe big fans run slower ? just a thought
  3. Mictlantecuhtli

    Mictlantecuhtli TechSpot Evangelist Posts: 4,916   +9

    The case fan is most likely 12 cm in diameter.

    Big fans don't need to spin fast to move the same amount of air as small ones.

    SiSoft Sandra doesn't always report temperatures and fan speeds correctly, usually because some mainboards have their proprietary ways of reading sensor data.

    I would trust BIOS much more than any application - except an external thermometer, maybe.

    Anyhow, 1900 rpm isn't low and 33C isn't high, in my opinion.
  4. Justin

    Justin Newcomer, in training Posts: 1,595



    Definately. I Agree.
  5. luvhuffer

    luvhuffer TechSpot Paladin Posts: 637

    A standard sized fan (80x80x25mm) can pull about 1-2 Watts. Large fans can pull about 7 watts. Mine (120x120x25) pulls 6 watts. That's a lot of draw through the mobo connector, and board. Watts = heat. I would suggest you run a large fan like that through a direct connection to the power supply with the standard 4 pin molex connector like the ones attached to the hard drives and ROMS. That way you will know the fan is running at full speed. But you won't be able to display the fan speed unless it's hooked up to a fan controller with a data display window. Also you may want to considered installing program that can monitor your temps and display them in real time like motherboard monitor 5
  6. Didou

    Didou Bowtie extraordinair! Posts: 5,899

    & you found it necesssary to reply to a one year old thread why ?
  7. luvhuffer

    luvhuffer TechSpot Paladin Posts: 637

    That's sure an interesting question. Especially since I wasn't looking at any posts past the first page. I never do. WTF? Oh well no harm no foul. But puzzling to be sure. Unless I pulled one off the similar threads box and didn't look beyond the 3/28 date.
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