A7N8X-X Fans Always Running

[KenW]

I have an A7N8X-X with an AMD 2500+ processor, Windows XP and an ATX
400 Watt 2.03 compliant power supply. My problem is that when I plug
the system in all fans (CPU fan, case fan, and dual power supply fans)
start to run continuously. No other components seem to come on. The
fans also continue to run when I shut the system down. Sometimes after
shut down the fans will stop briefly then start going again.

I've never seen this before on my other PCs and don't know what could
be the cause. I'd like to stop this to conserve electricity and my
fans. Any suggestions on what might be the cause?

 

[DL]

The cpu and psu fans will,by design, run constantly. If they dont, or you
stop them, you will fry yr hardware in no time. Assuming the overheat cut
out doesnt function.
Depending on yr setup the fans may have a speed control veried by sys load.
The only way to conserve electricity is to shut down.
Yr psu fan may run after shutdown I guess, if by design, but I have not seen
one that does.

 

[Paul]

I have an A7N8X-X with an AMD 2500+ processor, Windows XP and an ATX
400 Watt 2.03 compliant power supply. My problem is that when I plug
the system in all fans (CPU fan, case fan, and dual power supply fans)
start to run continuously. No other components seem to come on. The
fans also continue to run when I shut the system down. Sometimes after
shut down the fans will stop briefly then start going again.

I've never seen this before on my other PCs and don't know what could
be the cause. I'd like to stop this to conserve electricity and my
fans. Any suggestions on what might be the cause?

It could be a power supply problem or a motherboard problem.
For the PS to provide +12V to the fans etc, PS_ON# has to be
driven to logic low (0 volts). Normally, you would have to push
the buttom on the front of the case momentarily for this to
happen. As you note, something is not right.

Maybe you have a wiring error or a short somewhere. Perhaps the
power switch on the front of the case isn't hooked to the correct
pins, or an extra brass standoff underneath the motherboard is
shorting something. My computer displayed the same symptoms as
yours, when an IDE cable was installed crooked, so that not all
the pins touched. So, at least try reinstalling the wiring and
pull the motherboard, so the case can be removed as a source of
the short.

If the symptoms are reproducable after doing this, then I would
swap out the power supply and try another one.

HTH,
Paul

 

[Natéag]

I would rather think that the board is defective.
Possibly (but I really do not know), there may be a
shortcut connection through the standoff's to the case.

 

[KenW]

I have an A7N8X-X with an AMD 2500+ processor, Windows XP and an ATX
400 Watt 2.03 compliant power supply. My problem is that when I plug
the system in all fans (CPU fan, case fan, and dual power supply fans)
start to run continuously. No other components seem to come on. The
fans also continue to run when I shut the system down. Sometimes after
shut down the fans will stop briefly then start going again.

I've never seen this before on my other PCs and don't know what could
be the cause. I'd like to stop this to conserve electricity and my
fans. Any suggestions on what might be the cause?

Thank you all for your suggestions. The problem went away when I changed the
power supply.