PS fan on A7N8X-E deluxe

[Helpseeker]

I've got 2 A7N8X-E deluxe MBs. One about 8 months old, the other
brand new. Both are in Antec cases with different Antec PS (one is
true 550, the Other the ultra quite Sonata 380W).

Both of these PSs have a blue/blk 2 wire(3-position) connector to
connect to the MB "PS fan monitor connector"...

In both situations, NO PS fan speed is reported in the Bios nor Assus
probe.

I know the PS's are good as I tested in a 3rd system usingas Asus P4PE
and Intel MB and it reports ok. Also, I tried the MB "case fan"
connector...nothing....


HELP....

Running latest Bios on A7N8X-E

 

[DN]

To get the Power Supply fan in my Sonata case to register a speed on
Motherboard Monitor, I had to play with the fan type and divider settings.
It seems that if the fan speed is lower then 1300 RPM, the fan speed does
not show up in Motherboard Monitor. I have the same motherboard, and I have
never been able to get the fan speed to register in the bios.

 

[Paul]

I've got 2 A7N8X-E deluxe MBs. One about 8 months old, the other
brand new. Both are in Antec cases with different Antec PS (one is
true 550, the Other the ultra quite Sonata 380W).

Both of these PSs have a blue/blk 2 wire(3-position) connector to
connect to the MB "PS fan monitor connector"...

In both situations, NO PS fan speed is reported in the Bios nor Assus
probe.

I know the PS's are good as I tested in a 3rd system usingas Asus P4PE
and Intel MB and it reports ok. Also, I tried the MB "case fan"
connector...nothing....


HELP....

Running latest Bios on A7N8X-E

A fan pulses twice per revolution. The monitor chip uses a high
speed clock, to measure the number of counts between pulse edges

0123456789 <--- register contains 0x09
|<-------->|
__ __
| | | |
____| |_______| |______

As the fan speed drops, the pulses move further apart

0123456789ABC <--- register contains 0x0C
|<----------->|
__ __
| | | |
____| |__________| |______

The inverse of the measured period, yields the frequency
and thus the RPMs.

If the fan goes slow enough, the register contains 0xFF
That is the minimum speed that can be measured.
If the fan stops running altogether, the register will also
read 0xFF. The software has no way of knowing what the speed
is, once the speed drops below the minimum.

There is a programmable divider. It changed the rate of
the measurement clock. In this example, the sampling clock
is running at one half the speed of the examples above

0 1 2 3 4 5 6 <--- register contains 0x06
|<----------->|
__ __
| | | |
____| |__________| |______

Some monitoring programs allow changing that divider, and
then the minimum fan speed can be improved. The BIOS
uses divide by 2 as the default (AFAIK), and the monitoring
chip can do better than that.

HTH,
Paul

 

[Tim Dunne]

In

A fan pulses twice per revolution... 8<...

I'd just like to say what an excellent post that was. Nice one!

Tim