Boot Problem: Mobo/Power?

System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

--
Jim Garrison )
PGP Keys at http://www.jhmg.net RSA 0x04B73B7F DH 0x70738D88

hows the temps?

"Jim Garrison" wrote in message
...
System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

--
Jim Garrison )
PGP Keys at http://www.jhmg.net RSA 0x04B73B7F DH 0x70738D88

Jim Garrison wrote:
System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?


Between the DIMM slots, and the main power connector,
is the Standby Power Indicator LED. When the PSU is
switched on at the back, the LED should light, and it
should not wink or blink. It should remain on steady,
even when you press the power button on the front of
the computer.

If the Standby Power LED is flashing, it means +5VSB on the
power supply is cutting out. Either the supply is
weak, or the motherboard is overloading that rail of
the supply. The tie breaker, would be a clamp-on
DC ammeter reading on +5VSB. Without a meter, a
swap of the power supply might help.

Also, check the switch on the back of the PSU, that
sets whether the supply runs at 115V or 230V. Wavering
could be that switch set wrong. Be careful with that
switch! One moment's inattention, flipping it to the
wrong position, could mean kaboom, depending on what
country you are in.

Paul

Jim Garrison wrote:

System: Intel DG965WH in an Antec Sonata case with 450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing connected
to the PS is the motherboard. Is this more likely to be a power
supply problem or a motherboard problem?

Can be either. Obviously easier to try another power supply.

wrote:
On Sun, 04 Feb 2007 22:21:14 -0600, Jim Garrison wrote:

System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

First inspect the system board for a foreign object shorting
something out, turn over the case and shake it. Try again.

That shouldnt produce that recycling effect, it should shut down cleanly
and only restart once the mains is unplugged to reset the power supply.

No joy?
Unplug the system board, plug in one drive and ground pin 14
(usually a green wire) to a black one, see if it will spin up the drive.

Thats rather dangerous if the power supply is dying.

That should be enough load for the supply. If that holds you
are probably back to the system board. If you have a meter
you could check the voltages while it is spinning the drive,
just to be sure the supply is really working.

"Jim Garrison" wrote in message
...
System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

--
Jim Garrison )
PGP Keys at http://www.jhmg.net RSA 0x04B73B7F DH 0x70738D88
---------------------------------------------------------
Jim,

What memory do you have installed? That board requires 1.8V memory and is
very picky about memory in general. I saw identical symptoms on another
P965 chipset board when 2V memory was installed (constant power on-power
off, every 2 seconds or so, with only fans spinning for a moment.) It was
the memory causing the issue. See
http://www.intel.com/products/mother...ddr2/index.htm.

--
-Russell
http://tastycomputers.com

In comp.sys.ibm.pc.hardware.misc Jim Garrison wrote:
System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

Power supply. Very likely. The way PSU overload protection
works is that it checks the output voltages. If they are too low,
the PSU is shut down. Since the volgates need some time to stabilize
during power-up, this protection is activated with a small delay.
If one of the output voltages is faulty, then the PSU willstart
and stop as you observe.

You can test the PSU without the MB to verify this:

http://www.ee.surrey.ac.uk/Workshop/...s/connPSU.html

lists the contacts in the connector. To start the PSU, shorten
out pin 14 to ground, e.g. to pin 13 or pin 15. The PSU shoud run
as long as pin 14 is grounded. If it does the start-stop thing
you observed, then the PSU is broken. If it comes up and runns,
then it is unclear. Might still be the PSU or might be the MB
in the second case.

Arno

wrote
Rod Speed wrote
wrote

First inspect the system board for a foreign object shorting
something out, turn over the case and shake it. Try again.

That shouldnt produce that recycling effect, it should shut down cleanly
and only restart once the mains is unplugged to reset the power supply.

That is an awful broad statement without knowing what
brand machine this is or what power supply is installed.

Nope, thats what the ATX specs say should happen if it sees a short on one of its rails.

In comp.sys.ibm.pc.hardware.misc wrote:
On Mon, 5 Feb 2007 17:00:14 +1100, "Rod Speed"
wrote:

First inspect the system board for a foreign object shorting
something out, turn over the case and shake it. Try again.

That shouldnt produce that recycling effect, it should shut down cleanly
and only restart once the mains is unplugged to reset the power supply.

That is an awful broad statement without knowing what brand machine
this is or what power supply is installed.

The cycling effect could well be an interaction between mainboard and
PSU. Of course the PSU should shut down completely on a short and
require unplugging of the mains voltage to restart it. However that
might go over some peoples heads and so a PSU manifacturer could well
have choosen to accept a new (or even the old one) negative flank on
the /POWER_ON line. It might also save a few cents in components
and with the margins today cutting cost in this fashion would not
surprise me.

Arno

The only way to tell which is bad is to install a known working PSU and see
if that fixes it. (Much easier than first replacing the motherboard.)

--
DaveW

----------------
"Jim Garrison" wrote in message
...
System: Intel DG965WH in an Antec Sonata case with
450w PS.

Symptoms:

When I apply power to the system, the fans start but then
everything shuts down for about 1 second. This repeats
ad infinitum, and of course the sytem doesn't even get
close to running POST.

I have disconnected all peripherals, so the only thing
connected to the PS is the motherboard. Is this more
likely to be a power supply problem or a motherboard
problem?

--
Jim Garrison )
PGP Keys at http://www.jhmg.net RSA 0x04B73B7F DH 0x70738D88