Should the Pundit-R (or any barebones system for that matter) power-on
if there's no processor, RAM, or drive installed? I've started
machines without memory and drives, but not a processor.
Just trying to figure out whether I should get an RMA for the unit
while I wait for the components to arrive.
In all the hardware I've read about or helped people with,
there never seemed to be an interlock or other mechanism
that would prevent a bare board from allowing the power
switch to start up the power supply. A barebones could be
a bit different, because it consists of a lot of
subassemblies and wiring, and maybe the clever engineers
at Asus put some checks in the wiring headers, to detect
whether the more important wiring is connected to the
main board.
There is one circuit on Asus motherboards, that can stop
them dead, and that is "AGP Warn". AGP Warn is a circuit
that prevents a +3.3V I/O video card from damaging a
motherboard, and the presence of such a video card, prevents
the PS_ON# signal from being sent to the power supply.
Removing the video card means that circuit cannot do
anything, and would eliminate that as a source of failure
to start.
It is possible the PSU itself is not starting, or there is
no +5VSB being delivered. The PSU consists of two parts -
a +5VSB power supply, and the rest of the power supply.
The control circuit for the rest of the power supply is
powered by +5VSB. So, if +5VSB is shorted or not working,
then nothing is going to happen. If the motherboard in the
Pundit has a green LED, to indicate the presence of +5VSB,
check to see that is is lit, because if the LED is not
lit, then there is no way that pressing the power on
button on the front of the computer is going to start it.
On an ATX power supply, you can ground PS_ON# manually, while
the 20 pin power connector is disconnected from the
motherboard. At one time, I advocated this as a test
procedure, but someone rightly pointed out that this may
not be a suitable procedure for every power supply in the
world. I have a set of load resistors, so I can load up
the PSU while testing it, but without those resistors, there
is no way of knowing whether the PSU designer properly
handled the "no load" case or not. So, I cannot recommend
starting the PSU by itself, while it is disconnected from
the rest of your board. If the PSU is a standard ATX
supply, and you have an old computer that can be run
from a 250W ATX supply, you could always connect the
Pundit supply to the old computer motherboard, as a test
that the supply works. (If you value the old computer,
don't do this ;-)
HTH,
Paul
