To identify reason for failure, complete system - power
switch, motherboard control circuit, & power supply - is
described in this previous discussion: "I think my power
supply is dead" on 5 Feb 2004 in alt.comp.hardware or
http://www.tinyurl.com\2musa

That 3.5 digit multimeter is necessary to actually 'see'
what is happening; to understand the interplay between those
three system components. Even if problem is not supply, an
appreciation of what does happen is useful knowledge.

mr x wrote:
Old PC Occasionally Won't Start, Doesn't Power Down all the time
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I have several computers, but I am having a problem with an old
computer I keep around for testing/experimenting purposes (trying
out new OS's, and generally tinkering with).

This computer is an old gateway g6-300, Pentium II 300, 128MB ram,
8.4 maxtor hdd

A couple of weeks ago I hit the power button and nothing happened.
I hit it again and again. nothing. I was getting ready to leave to
do some errands and didn't have time to fool with it, so I left it
for the time being.

A day or two later I went to start it and it started no problem.
It currently has win98se with most of the MS win98 updates
installed. I also noticed if I choose "restart" for the shut down
menu, it acts like it's going to shut down, you see the win 98
"your computer is shutting down." screen, the screen goes black,
but the computer doesn't shut down (lights are still on and I hear
the fans going).

However if I choose "shut down" from the shut down menu, it does
actually power down all the way.

Last night it also did a strange thing where after I pressed the power
button, it began to power up and then shut itself off after about 4-6
seconds. I hit the power button again and it did the same thing. Again
and it did it a third time. I un plugged in and plugged it back in and
hit the power button again and suddenly it powered on normally.

I am guessing perhaps the power supply is starting to go, and I am
wondering if anyone out there has experienced a total or partial
power supply failure. I have never actually had a power supply go on
me before. Does this sound like what might be happening? I don't
have another power supply lying around to swap out and see if it
makes a difference. I also don't have a multimeter or any equipment
to test the power supply on hand ( I guess I know what I may need to
get if I really want to get to the bottom of this).