power switch won't boot up?

[Larry Gagnon]

I have the following strange behaviour on my NF7-S motherboard with an
Antec case. Most of the time when I turn on the computer with the front
case power-on switch the fans, HD and CDROM start up, but the machine
won't actually boot until I hit the reset switch.

However, if I turn off the power supply at the rear main switch,
turn it back on again and then hit the front panel power switch it
DOES boot without using the reset switch. It will also boot from the
power switch if I have only recently turned the the machine off. If it
has been sitting dormant for any length of time I must use the reset
switch after power-on to get a boot.

I have checked the wiring of my switches to the MB and they seem fine.

Any ideas why?

Larry Gagnon

 

[kony]

I have the following strange behaviour on my NF7-S motherboard with an
Antec case. Most of the time when I turn on the computer with the front
case power-on switch the fans, HD and CDROM start up, but the machine
won't actually boot until I hit the reset switch.

However, if I turn off the power supply at the rear main switch,
turn it back on again and then hit the front panel power switch it
DOES boot without using the reset switch. It will also boot from the
power switch if I have only recently turned the the machine off. If it
has been sitting dormant for any length of time I must use the reset
switch after power-on to get a boot.

I have checked the wiring of my switches to the MB and they seem fine.

Any ideas why?

Larry Gagnon

Might be the power supply, perhaps inadequate on it's 5VSB rail. If
your board has jumpers to power USB and/or PS/2 ports by the 5VSB
(might be termed power-on [by device]) set them to main 5V rail, not
5VSB, see if that helps.

You might also take voltage readings from the power connector(s), 5VSB
while the system is off (but plugged into AC of course) and from
motherboard connector for 3V while system is in on-but-no-POST state
(and 5V, 12V from any connector).

If your power supply has connectors for fan-only, make sure they're
only powering fans.

What model power supply? How long has the system been running
properly in it's current configuration, without any changes?

You might try underclocking the CPU, video card, see if that reduces
power consumption enough to make a difference. Is there any sign of
instability once they system is up & running the OS?