The best way to test for PSU problems is to leave everything
in the system, get a multimeter, and take voltage readings.
What to measure is listed in "I think my power supply is
dead" in alt.comp.hardware on 5 Feb 2004 at
http://tinyurl.com/yvbw9 .
You readings should appear in the upper 3/4 limits of that
chart - especially for 3.3, 5, and 12 volt outputs. This
takes but seconds.

That to determine if power supply is functioning properly.
Next you want to determine if power supply is being
overloaded. Just because they printed 300 watts does not mean
it really is 300 watts as Tom's Hardware demonstrates in
http://www6.tomshardware.com/howto/0...021/index.html

Furthermore, any one voltage with too much load means the
entire power supply has failed. So again, you take that
essential 3.5 digit multimeter to measure same voltage as load
is increased. For example, write a little *.bat file to read
each disk drive repeatedly. One example:
:ABC
dir c:*.* /s
goto abc

This file would continuously read directories on the C:
drive. Another *.bat file executing simultaneously might read
the A: floppy. A third read the CD-ROM. Another might read a
disk on another computer via the NIC. Now we have full
loading. What happens to the voltages? Do they remain well
within those same limits? If yes, the power supply also has
sufficient power on each voltage.

Notice how quickly a PSU can be verified with confidence not
even provided by 'shotgunning' - keep swapping parts until
something appears to work.

Bottom line - don't start fixing anything. First collect
facts to identify the suspect. Even if you don't understand
those numbers, still, those number make it possible for the
informed to help you. No numbers and no specific facts means
you must shotgun. Shotgun is what you scam mechanic does - the
guy you never go back to.

Get the meter. Use to to see what the entire power supply
system is doing as also described in "Computer doesnt start at
all" in alt.comp.hardware on 10 Jan 2004 at
http://tinyurl.com/2t69q

It is how one works smarter and not harder. One also learns
that a real 300 watt supply is more than sufficient for most
every computer. Don't fall for the Home Improvement concepts
of "more power". First see the problem.

Dan B wrote:
I have a 300 watt PSU powering AMD Athlon 64 3000+, 512Mb PC3000,
GeForce 6600 GT AGP and a seagate 200 gb sata drive. Nothing else at the
moment. Sometimes the computer will just fail to start even though
nothing has changed since the last time. I have to clear the CMOS and
even then it will sometimes not work.

Could my PSU need an upgrade?

Regards

Dan B