What's the PWR_FAN header for?

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milleron

On my A8N-SLI Premium, one of the fan headers is labeled "PWR-FAN."
I've assumed that it's the proper place to connect the three-pin fan
header plug from my PSU (Antec TruePower II). I don't think the
manual says anything more about it than to label it.
Clearly, it would NOT be there to provide power to that particular
fan, so I deduce that it's there to provide rpm monitoring for the PSU
fan.

But the only fan speeds I can find reported are the CPU and the
CHA1_FAN. This is true in BIOS, Asus Probe, Lavalys Everest, and
nVidia Monitor. What am I missing or misunderstanding here?

Thanks,

Ron
 
On my A8N-SLI Premium, one of the fan headers is labeled "PWR-FAN."
I've assumed that it's the proper place to connect the three-pin fan
header plug from my PSU (Antec TruePower II). I don't think the
manual says anything more about it than to label it.
Clearly, it would NOT be there to provide power to that particular
fan, so I deduce that it's there to provide rpm monitoring for the PSU
fan.

But the only fan speeds I can find reported are the CPU and the
CHA1_FAN. This is true in BIOS, Asus Probe, Lavalys Everest, and
nVidia Monitor. What am I missing or misunderstanding here?

Thanks,

Ron
Click to expand...

See 2-24 of the manual (PDF), it's just another fan header.
 
On my A8N-SLI Premium, one of the fan headers is labeled "PWR-FAN."
I've assumed that it's the proper place to connect the three-pin fan
header plug from my PSU (Antec TruePower II). I don't think the
manual says anything more about it than to label it.
Clearly, it would NOT be there to provide power to that particular
fan, so I deduce that it's there to provide rpm monitoring for the PSU
fan.

But the only fan speeds I can find reported are the CPU and the
CHA1_FAN. This is true in BIOS, Asus Probe, Lavalys Everest, and
nVidia Monitor. What am I missing or misunderstanding here?

Thanks,

Ron
Click to expand...

The Premium manual lists CPU, CHA1, CHIP as the three fan
speed monitoring channels. It would seem they ran out of
channels, and considered the CHIP header to be more important
than the PSU header. Now, normally, there would be no need
to put +12V on that header, but perhaps +12V and GND are the
only connections.

Assuming your board has an ITE IT8712 hardware monitor chip,
there are actually five fan control channels and five fan
monitoring channels. If the motherboard has a GAME/MIDI header,
two pins from the fan control group and two pins from the
fan monitoring group, are hijacked to make joystick interface
pins. That leaves three channels of fan control and three
channels of RPM monitoring. Seeing as the manual lists
CPU, CHA1, CHIP as the monitor headers, any other headers
are at best just power plugs for fans. You could check to see
if they have power, by plugging in a fan (with the power off!).

Paul
 
The Premium manual lists CPU, CHA1, CHIP as the three fan
speed monitoring channels. It would seem they ran out of
channels, and considered the CHIP header to be more important
than the PSU header. Now, normally, there would be no need
to put +12V on that header, but perhaps +12V and GND are the
only connections.

Assuming your board has an ITE IT8712 hardware monitor chip,
there are actually five fan control channels and five fan
monitoring channels. If the motherboard has a GAME/MIDI header,
two pins from the fan control group and two pins from the
fan monitoring group, are hijacked to make joystick interface
pins. That leaves three channels of fan control and three
channels of RPM monitoring. Seeing as the manual lists
CPU, CHA1, CHIP as the monitor headers, any other headers
are at best just power plugs for fans. You could check to see
if they have power, by plugging in a fan (with the power off!).

Paul
Click to expand...

Thanks, Paul. So it looks as though the header marked "PWR_FAN" is,
in reality, for any fan OTHER THAN the "PWR FAN" because all the PSU
fan requires is rpm monitoring, but the only thing that header
actually provides is power. Asus was really stupid on this one, then.

Ron
 
See 2-24 of the manual (PDF), it's just another fan header.
Click to expand...

Thanks for the reply, but I did read the manual before posting.
Although the PWR_FAN header is pictured there on 2-24, it certainly
does not state that it's "just another fan header" and definitely does
not say anything about its rpm-monitoring capability. In fact, it
gives no information about it (other than that it's not governed by
Q-Fan), which is why I posted the question here.



Ron
 
Some power supplies have a separate lead that can be plugged into the Fan
Header on the motherboard. The motherboard will then controll the power
supply fan or it will just monitor the speed of the fan.
 
RonK said:
Some power supplies have a separate lead that can be plugged into the Fan
Header on the motherboard. The motherboard will then controll the power
supply fan or it will just monitor the speed of the fan.
Click to expand...

Yes, my Antec NeoPower 480 has a 3-pin fan sensor on it.
The trouble is that the A8N-SLI Deluxe does not give you the ability to read
the RPM anywhere.
There is nothing in the BIOS, Asus Probe does not show the reading either.
So far I have tried:

Sandra
Speed Fan
MBM5
Everest

And not one of them is able to read the information form the header.
 
On the P4C800 the header reads the power supply fan fine, if you have a
supply with the lead. It outputs it to the Asus Probe program. Funny they
wouldn't do that on your board as well.
 
On the P4C800 the header reads the power supply fan fine, if you have a
supply with the lead. It outputs it to the Asus Probe program. Funny they
wouldn't do that on your board as well.
Click to expand...

Well, this board does have a game-port header, so, as Paul explained,
Asus seems to have pirated a connection from the PWR_FAN header to
make the game port functional. It's the best explanation I've had so
far. I have my PSU plug connected to the PWR_FAN header, and there's
no readout ANYwhere.
Too bad, because I'm really curious about how much variation there is
in the TruePower II's fan.
Interestingly, Paul has a reference stating that on my board, the CHIP
header provides monitoring. However, I do have a small 80mm fan with
rpm sensing connected there, and there's no readout for that one,
either. The only two I can see are CPU and CHA1_FAN which, probably
not coincidentally, are the only two headers on this board controlled
by Q-Fan.

Ron
 
I've got an Antec 480 and it typically runs at about 1850 rpm at idle and
maybe 2300 rpm in 2D Apps. In 3D games it typically runs at about 4500 rpm.
This is with ambiant room temps of about 82 degrees this time of year.
 
are you sure it's not a "vre" header ? Maybe it is in fact just a
miss- labelled power fan header...

Like paul suggested, just plug a fan into it and see if it is powered.

Another thing you could try is disconnect the chassis fan header and
hookup the fan to the pwrfan header...now check you bios. It may be
visible there now and the limitation is that only 2 headers may be
reported at any one time. This was the case with an intel board I
had...
FYI
 
I have my PSU plug connected to the PWR_FAN header, and there's
no readout ANYwhere.
Too bad, because I'm really curious about how much variation there is
in the TruePower II's fan.
Click to expand...

Just plug it into the RPM-monitored header that isn't the CPU fan. Since
the PSU fan isn't powered by header, any fan-speed control of the board
won't affect it, you'll just get the current rpm readout.

Cheers - Jaimie
 
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