Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <0m5d91pnmgv2oq9mnj8osrmi6g2l6c13kr@4ax.com>, me@privacy.net wrote:
> On Thu, 26 May 2005 18:51:50 -0600, "Mark A" <nobody@nowhere.com> wrote:
>
> >>"Brad Clarke" <me@privacy.net> wrote in message
> >>news:etqc91ptt2jodr9uhhvml92uubupv2hj31@4ax.com...
> >>> My A7V400-MX only seems to have the chassis and CPU sensors connected
> >>> (Antec case & psu).
> >>>
> >>> PC Probe always shows the power fan at 0, even though the fan in the psu
> >>> is running.
> >>
> >>Your PSU would have to have a fan monitor cable (not all do), and you would
> >>have to plug it into the correct MB connector for the PC Probe to see the
> >>RPMs.
> >>
> >>It's not magic.
> But it could be

>
> The specs on my board indicates it only has monitoring capabilities for
> the CPU fan and one chassis fan.
The number of fans monitored is determined by the monitor chip.
There are chips that have two fan monitors and chips that have
three fan monitors.
When a motherboard has three fan headers, and a chip with two
fan monitors, one of the headers simply doesn't use the tachometer
signal that comes from the fan. I would presume the unimplemented
channel would read zero in Asus Probe.
Some of the monitor chips, also have Q-fan type support for all
channels. But, Asus only puts one power transistor on the motherboard,
for control of the CPU fan header. Some of the newer motherboards
have Qfan2, which allows the CPU fan header and a second fan header
to be controlled by the monitor chip. A program like speedfan cannot
know how many channels have power transistors - while speedfan
can attempt to adjust a channel in the monitor chip, if there is
no driver transistor on the board, then nothing will happen (i.e.
fan continues to run full speed).
To see what a typical chip looks like, try this doc.
http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/627hf.pdf
HTH,
Paul