Fooling motherboard into booting without CPU fan

Discussion in 'Gigabyte' started by Michael Strorm, Oct 6, 2003.

  1. Hi,
    Is it possible to fool a motherboard into booting even without the
    fan attached (assuming it checks the rotational speed before
    I thought shorting the 'SENSOR' and 'GROUND' pins would work at
    first, but if it's being used to detect the fan speed, then maybe not?
    The CPU_FAN connector on the Gigabyte motherboard has 3 pins
    (SENSOR, 12V and GROUND), if that's relevant(?).
    Any help would be appreciated, thanks!

    - Michael Strorm
    Michael Strorm, Oct 6, 2003
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  2. Michael Strorm

    Will Dormann Guest

    You should be able to go into the BIOS and disable the CPU fan check. I
    do this, as my CPU fan is 2-wire.

    Will Dormann, Oct 6, 2003
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  3. Michael Strorm

    jpsga Guest

    use a 1.5v battery between the 3rd pin and ground. My 4000RPM fans run
    around 1.7 volts.on the tach side.
    jpsga, Oct 6, 2003
  4. Michael Strorm

    kony Guest

    That sounds like a bad idea, it is not a voltage level being detected
    from the fan, it's the pulse rate.

    Neither should the sense pin be grounded. The poster who mentioned a
    bios setting to disable the fan error-stop was correct.

    kony, Oct 6, 2003
  5. Yeah, that's what I suspected... :-(
    Good idea, but the power to the machine cuts out after a fraction of a
    second, so it's not an option.

    Given that (supposedly) an Athlon without the heatsink can fry in
    under a second(!!), this is not surprising, but it does mean I can't
    do anything with the BIOS.

    - Michael S
    Michael Strorm, Oct 6, 2003
  6. Michael Strorm

    kony Guest

    On 6 Oct 2003 03:41:52 -0700, (Michael Strorm)

    I'm surprised the bios doesn't display a warning for a bit before that
    happens. You don't have ANY fans with RPM you could attach to the
    header just long enough to enter BIOS setup and change that setting?
    Doesn't necessarily need to be sitting on the heatsink, just plugged
    into the appropriate fan header. Perhaps another chassis or PSU fan
    has the tach-output (RPM signal) feature, so you could temporarily
    sway these fan plugs from their respective headers?
    True, but that's only without the heatsink itself... with the heatsink
    on but no fan it'd run for at least dozens of seconds, maybe several
    minutes before locking up (depending on other factors), and the temp
    increase rate would be slow enough that the motherboard temp shutdown
    feature could react and shut down the system.

    kony, Oct 6, 2003
  7. Michael Strorm

    Barry Walsh Guest

    You can turn the protection off in the BIOS, where it's labelled
    Guardian Function. You'll just need something connected enough to get it
    to the BIOS.
    Barry Walsh, Oct 6, 2003
  8. Michael Strorm

    Barry Walsh Guest

    It just occured to me that this may also exist as a jumper rather than a
    BIOS option.
    Barry Walsh, Oct 6, 2003
  9. Michael Strorm

    GTD Guest

    Some motherboards default to this protection being OFF. Mine does, and
    I know this works because it is a watercooled system with no fans
    connected to the motherboard headers, and I have discharged the cmos
    afted updating the bios, and never had to use a fan or anything to get
    into the bios. I'd try discharging the cmos, or boot with default
    settings and see if it works.
    GTD, Oct 7, 2003
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