ASUS A8N-SLI Premium CPU Fan Warning Problems

Discussion in 'Asus' started by davem, Nov 7, 2005.

  1. davem

    davem Guest

    I'm in the process of building up a new computer using an ASUS A8N-SLI
    Premium this motherboard and an AMD Athlon 64 C2 4400+. I have just
    finished installing all of the components into the case and have
    performed the initial computer power to verify that everything comes up
    and that I can access the BIOS.

    When I start up the computer I get a POST error indicating that the CPU
    Fan is not working. I can visually determine that the fan is working
    but when I go into the BIOS and check the hardware reporting section,
    it tells me that the fan speed is 0 RPM. I can over-ride the warning
    message everything else seems to be as expected.

    I have installed an aftermarket Thermalrite XP-90 CPU heatsink with a
    Panaflo 90mm FBA09A fan on the heatsink. This fan has a sense lead and
    I have checked for continuity on the three wires to the fan and all of
    the wires are good. I have substituted a NEXUS three wire fan on the
    motherboard CPU_Fan connector and get the same results. I have also
    tried the smaller three wire fan that came with the stock CPU heatsink
    and strangely this fan seems to work correctly and I don't get a POST

    This seems strange to me as both of the non-AMD fans have sense leads
    but the POST reports 0 rpm fan speed yet the stock fan seems to report

    I would appreciate any suggestions that others might have regarding
    what is going on. I would like to stay with a lower noise fan and want
    to stay with the larger aftermarket heatsink but I'm sort of stalled as
    I can't figure out why the aftermarket fans aren't reporting rpm to the

    The BIOS that came with the motherboard is 1007 and I haven't made any
    attempt to update to one of the later versions. Also, I haven't loaded
    Windows XP and probably won't until I understand better what is going

    Thanks in advance for your help.

    Dave M
    davem, Nov 7, 2005
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  2. davem

    milleron Guest

    This sounds familiar. I had no problems with a nice 120mm Thermaltake
    CPU fan on this board. I replaced it with a 3-wire Panaflo, because I
    wanted it to be a little quieter. Well, the computer is a tad
    quieter, but the Panaflo RPM sensor is definitely flaky. I'm
    constantly finding that POST has paused because "the CPU fan failed to
    start" (I can't recall the exact wording of the message) even though
    the fan is spinning merrily away and maintaining a CPU temp of 30°.
    It's a simple matter to ignore the message by hitting F1 and allowing
    POST to proceed, however, it's aggravating. I'm guessing that the
    Panaflo sensor is for some weird reason somewhat incompatible with the
    monitoring chip on the A8N-SLI Premium.

    I'm still running BIOS 1004, but I really don't think this has
    anything to do with the BIOS. The BIOS is looking for a signal from
    the monitoring chip, but it's simply not getting it with some fans. I
    doubt that going to 1008 or 1009-beta is going to help. I've had good
    luck with Antec TriCool fans -- i.e., they're reasonably quiet, and
    the Thermaltake Thunderblade fan I replaced wasn't that noisy, either.
    I'd suggest picking up one of those brands.

    milleron, Nov 7, 2005
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  3. Same thing happens to me with the stock-standard Intel cooler on my P5LD2
    board. The only way to stop it happening - aside from setting the fan to
    run at full speed 24/7 - is to set it to "performance mode". This is the
    only mode that doesn't produce a "CPU Fan Fail" error during POST.
    Anthony Horan, Nov 7, 2005
  4. davem

    davem Guest

    Thanks all,

    I guess that I will just have to monitor things for a while once I have
    the system fully built. In the mean time, I have just turned off the
    warning in the BIOS.

    Dave M
    davem, Nov 7, 2005
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