Archived from groups: alt.comp.periphs.mainboard.asus (More info?)
In article <firstname.lastname@example.org>, Jay Peterman
> After my computer stopped booting I asked for advice. I was advised it
> was more than likely the power supply. I purchased an Antec 400 watt
> supply which fixed the problem (Thanks to DaveW and Paul).
> I noticed that the fan on the MB still did not start up. Someone
> advised that I check the BIOS for fan information. The BIOS did not
> have any info on it.
> The fan on the MB is not directly connected to the power supply.
> I found the CD with the Probe Utility on it and installed it.
> Here is info that it provided:
> On the Monitor Summary page:
> CPU Fan, Power Fan and Chassis Fan
> "below threshold" is flashing.
> On the Temperature Monitor page:
> The temperatures are below the threshold
> On the Fan Monitor page:
> Flashing zeroes
> Settings page:
> CPU Fan - 2200 rpm
> Power Fan - 1200 rpm
> Chassis Fan - 1200 rpm
> On the Fan Monitor page the graph shows that the thresholds are set to
> the above settings.
> The board is a P4S8X, PIV 2.4GhZ. There is a BIOS available which I
> downloaded from their site but I'm taking a slow "learn everything
> before" type approach to that.
> My question is should the MB fan be running all the time or just when
> needed? The top of the computer case appears a little warmer than
> normal. Thanks for any help.
When you refer to "MB fan", are you looking at the fan on top of
the CPU heatsink when you say that ? The diagram in the manual for
the board, doesn't show a fan on the Northbridge - are you looking
at the Northbridge chip ? (it sits just below the processor socket)
There are three fan headers on the motherboard. CHA_FAN, CPU_FAN,
PWR_FAN. These are monitored in the BIOS in Power Menu:Hardware Monitor.
The CPU_FAN, according to the BIOS page, has Q-Fan control. This
is disabled by default. Q-Fan adjusts the fan speed, ramping the
fan up between 50C and 60C measured CPU temperature. On older boards,
Q-Fan will always make the fan spin, as it still supplies some
voltage to the CPU fan at all times. So, to start with, you can
check and make sure Q-Fan is disabled, so the CPU fan can run at
full speed if it is able.
The second issue, is each fan header has a current limit. The manual
lists 350mA per header. If more than 350mA is needed, generally you
should purchase an adapter that plugs into a disk drive cable to
get the necessary +12V power. Such an adapter will include a male
and female fan connector, and one of those connects to the motherboard
to deliver the RPM (tachometer) signal, so the BIOS can monitor the
The fan speed listed in the BIOS can be registering zero for a couple
of reasons. Some fans have no RPM signal (only two wires go to the
three hole connector). If the fan spins below some threshold value
(maybe 1800RPM), sometimes this leads to the BIOS reading the value
as zero. Asus Probe might be a little smarter about this.
So, what reasons are there for a fan to be dead ?
1) Fan header is dead. If you shorted the fan header at some
point, or used a monster fan that draws an amp of current at
+12V, then some component between the fan header and the
ATX power 20 pin connector could be burnt. In this case, there
really isn't a reason for such a component on the CHA_FAN or
the PWR_FAN header, but the CPU_FAN has the Q-Fan transistor
and it can get damaged.
2) Fan is dead. Electrical failure.
3) Fan cable is unplugged or oriented incorrectly. An incorrect
orientation (i.e. thwarting the key on the connector by
jamming it) could damage the fan.
4) Fan rotor is jammed with dirt.
5) Sleeve bearing fans with no oil and loose tolerances can jam
due to wobble.
I test fans here, by using a nine volt battery and one of those
nine volt battery clips with the red and black wires on it. I
touch red to red and black to black, to connect 9 volts to the
12 volt fan. This runs the fan at less than full speed, but it
does tell me that the fan is OK. As mentioned in (3) above, you
have to be absolutely certain of polarity when doing this,
because AFAIK fans don't have polarity protection (I haven't
tested this, cause I like all my fans :-)
If you have managed to burn your fan headers, all is not lost.
Of the three signals, +12V, GND, RPM, typically the RPM is still
good. If you buy a fan power adapter, you can adapt all the fans
to run from a disk drive cable, and still plug the single wire
plus three hole connector, to the individual fan headers, so the
RPMs can be monitored.
Here is a sample picture of an Antec fan power adapter. There
are two adapters in this picture, because they are sold two to
a package for this product. This particular model has no "daisy
chain" capability - some adapters have a male and female four
pin disk drive connector, so you can chain three adapters together,
wasting only one disk drive connector on the PSU.
As for the BIOS, I wouldn't reach for the flashing program just
yet. If you want to flash a BIOS, _first_ check for warnings
about which Asus flash methods don't work with a particular
BIOS release. This info is on the download page, can be seen
by clicking the "More" link, and usually shows up on the final
download (server choice) page. The DOS boot floppy method is the
most stable, and the computer should be in a stable state before
you flash (no overclock, no power failures expected or computer
is fed by a UPS, etc). Double and triple check you have downloaded
the correct file - many dead boards are a result of grabbing the
wrong file. Doing a Google search using the motherboard name
and keyword "flash", may uncover cases of boards killed by flashing,
and reading up on the root cause (what people did wrong) may
help prevent you from joining them. If the board does fail to
post, the alternative is to contact badflash.com and buy a
replacement flash chip. For the "four sided" PLCC flash chips,
it pays to pick up an extractor tool, as it helps pull the chips
out flush to the motherboard. These cost $10 at Radio Shack for
a chip extractor or some companies include a cheaper version of
the tool with the replacement flash chip.