ASUS A7N8X-E Fan RPM Reads Zero Problem RESOLVED (Sort-Of)

[Guest]

Archived from groups: alt.comp.periphs.mainboard.asus,alt.comp.hardware (More info?)

Hello,

I have a new ASUS A7N8X-E motherboard which shows fan RPM as ZERO
except for the case that the fan is actually being POWERED from the +12V
terminal of the three-pin fan header. Now this is not a problem for the chassis
fan; but it IS an issue with the Power Supply Fan (draws power internally
from the PS) and the CPU fan which is a high-performance model that exceeds
the load capacity available from the fan header (350mA ~ 740mA).

Both the PS and CPU fans provide a fan speed sense connector for the purpose
of RPM monitoring. The PS has wires for both ground and RPM sense. The CPU
fan has only a wire for the RPM sense. Until I ran across this board, the RPM of
both of these could be read out without difficulty despite the fact that they drew
power from another source.

I flashed the board to the LATEST BIOS and the problem still persists. Anybody
know of a way to get around this problem? What would happen if I were to put some
kind of artificial load on the +12V fan header output? Would the ground line also have
to be connected?

*** THESE THINGS USED TO WORK JUST FINE "AS IS" IN THE PAST!!! ***


TO ASUS:
-----------------------
Is this a design flaw or was it done on purpose? Obviously, I MUST be able to
monitor these CRITICAL fans - otherwise I could fry an expensive PS and CPU should
a fan go down and I'd not get any alarm (because I'd have to disable it in order to run
with this board). Yes, over-temp should catch the CPU but by then it may be too late!!
I don't know what protection the PS has built into it (an Antec True 430-watt).

TO AJUMP.COM:
-----------------------
If this cannot be repaired (meaning this is a design flaw - EVERY board will exhibit
the problem) how do I get my money back on it? I also am worried that the ASUS
A7V880 I just had you guys replace under RMA may have the same issue!! I am going
to test this theory as soon as possible. What happens if I have to RMA BOTH boards
requesting refund of the purchase price? Reply to my e-mail as per the instructions in my
signature (or look up customer #11A048238). Thanks.

=====
You may send e-mail if you wish provided it is NOT SPAM. To decode my valid
E-mail address, you will need to remove the <NOSPAM.> and the <666>. I had
to get complicated as spammers are now doing the obvious removal of the word
"NOSPAM" to compile their lists of e-mails...

- G.L. Cross

 

[Guest]

Archived from groups: alt.comp.periphs.mainboard.asus,alt.comp.hardware (More info?)

On Tue, 28 Sep 2004 04:00:28 -0500, "G.L. Cross"
<gordoncross6663@NOSPAM.charter.net> wrote:

>Hello,
>
>I have a new ASUS A7N8X-E motherboard which shows fan RPM as ZERO
>except for the case that the fan is actually being POWERED from the +12V
>terminal of the three-pin fan header. Now this is not a problem for the chassis
>fan; but it IS an issue with the Power Supply Fan (draws power internally
>from the PS) and the CPU fan which is a high-performance model that exceeds
>the load capacity available from the fan header (350mA ~ 740mA).

Use a different fan. There is no CPU you could run in that
board that needs 350-740mA fan. Even 250mA is excessive
unless you have very poor heatsink.

Let's suppose you're trying for a potentially-damaging,
extreme overclock... In that situation, you'd need water
cooling or other exotic measures, and a board that uses 12V
for CPU power. That board uses 5V, and will drop the
voltage too much before you'd ever begin to need 350mA fan.


>Both the PS and CPU fans provide a fan speed sense connector for the purpose
>of RPM monitoring. The PS has wires for both ground and RPM sense. The CPU
>fan has only a wire for the RPM sense. Until I ran across this board, the RPM of
>both of these could be read out without difficulty despite the fact that they drew
>power from another source.

Maybe your board is defective?
Maybe you've blown out the fan header somehow?
Maybe someone has falsely lead you to believe your goal is
more important than it is?

The number one way to combat fan failure is to use a good
quality fan at moderate RPM. If you fear yours will fail,
you should replace the fans now with something better...
regardless of whether it works with RPM monitoring on your
board.


>
>I flashed the board to the LATEST BIOS and the problem still persists. Anybody
>know of a way to get around this problem? What would happen if I were to put some
>kind of artificial load on the +12V fan header output? Would the ground line also have
>to be connected?

Artificial load will get you nothing.


>
>*** THESE THINGS USED TO WORK JUST FINE "AS IS" IN THE PAST!!! ***
>
>
>TO ASUS:
>-----------------------
>Is this a design flaw or was it done on purpose? Obviously, I MUST be able to
>monitor these CRITICAL fans - otherwise I could fry an expensive PS and CPU should
>a fan go down and I'd not get any alarm (because I'd have to disable it in order to run
>with this board). Yes, over-temp should catch the CPU but by then it may be too late!!
>I don't know what protection the PS has built into it (an Antec True 430-watt).


To user: We do not support this configuration. Attach
normal lower amperage fans to each header to see if the
function works. Clear CMOS and try again. If fan headers
then do not work your board is defective.


>TO AJUMP.COM:
>-----------------------
>If this cannot be repaired (meaning this is a design flaw - EVERY board will exhibit
>the problem) how do I get my money back on it? I also am worried that the ASUS
>A7V880 I just had you guys replace under RMA may have the same issue!! I am going
>to test this theory as soon as possible. What happens if I have to RMA BOTH boards
>requesting refund of the purchase price? Reply to my e-mail as per the instructions in my
>signature (or look up customer #11A048238). Thanks.

Multiple boards having same problem?
I'm beginning to suspect that you're wiring something wrong
or that the fans don't actually have RPM output, maybe a
stall sensor lead instead, which isn't compatible with
motherboard headers. On the other hand you report that it
worked previously, so two possibilities I see:

Power supply fan is thermal-controlled by power supply, and
it's RPM is too low to register (not uncommon). One hopes
for a bios update to address this, but it may or may not
ever come. Fan without RPM (thermal) control and more
common RPM (like 2200-5000) should be tried on that header
to rule out damage or defect.

CPU fan above monitor's tolerable range, RPM TOO high.
Perhaps not, it's far less common but then it's not common
to use such a high-powered fan either. When a fan header is
calibrated to register smaller range of values, it should
have higher accuracy(?) so it's not necessarily a bad thing
for most people.


Use high quality fans and moderate RPM and don't worry about
fan failure till it happens, OR replace motherboard, hoping
for luck from Asus or vendor. I'd choose the former.