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
error.

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
correctly.

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
BIOS.

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
on.

Thanks in advance for your help.

Dave M

On 6 Nov 2005 20:04:29 -0800, "davem" <(E-Mail Removed)> wrote:

>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
>error.
>
>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
>correctly.
>
>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
>BIOS.
>
>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
>on.
>
>Thanks in advance for your help.
>
>Dave M

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.


Ron

On Mon, 07 Nov 2005 05:18:22 GMT, milleron wrote:

> 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.

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.

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


Anthony Horan wrote:
> On Mon, 07 Nov 2005 05:18:22 GMT, milleron wrote:
>
> > 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.
>
> 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.