John Keiser wrote:
Paul,
If I may impose on your knowledge of PSUs, can you help me with an earlier
post?

I have a Acer Verition M460 [AMI BIOS R01-C3] with WindowsXP SP3.
I had the CMOS set to wake and boot every morning. Worked fine for several
years.
Then intermittent, now not at all.
In the morning the power light is on and the NIC light is sometimes on.
Screen has no info and the PC has stopped short of actually booting [so
Event Viewer has no info]. I simply hold the power button 3 seconds and
repower up. Always successful.
Time/date is accurate but I changed the CMOS battery and re-enabled the RTC
alarm.
I also changed the PSU.
No joy.
Obviously not a major issue but I am curious, any idea why this is
happening?
Thank you.


When I google on Veriton M460, I'm seeing a higher than normal number of
problems there.

http://forums.techguy.org/virus-othe...e-related.html

http://forums.majorgeeks.com/showthread.php?p=1418793

Things you'd need to list in your query:

1) Was the system in S3 suspend to RAM, or S4 Hibernate, or just shutdown from the menu ?
If you were starting up in the morning from S3, then the RAM could have an issue.
(I have one machine here, that won't reliably start from S3 the next day. The RAM
is good, so that's a motherboard problem. The motherboard can't retail memory contents
overnight.)

If S4, then perhaps the drive isn't "becoming ready" within the timeout interval.
If you're starting from a complete shutdown, that would be about the same scenario
as Hibernate. Does the hard drive diagnostic that you can download for it, pass or not ?
Seagate and Western Digital offer diagnostic programs. (Make sure you've
burned the recovery media for your PC, in case the hard drive needs to be
replaced at some point. Backups to an external hard drive would be nice as well.)

2) Have you tested with some other boot scenario ? For example, set the wake up time,
do a shutdown from the Windows menu. Then, plug a floppy diskette with a copy of
memtest86+ on it, into the floppy drive. When the system starts the next time, as
long as the floppy is first in the boot order, it'll boot from the floppy. The purpose
of this kind of test, is to try to remove the hard drive from the picture. Even better,
would be to unplug the hard drive data cable (so the system can't get hung up,
while probing the hard drive).

http://www.memtest.org (scroll half way down, get the download, use the program
to prepare a boot floppy. After prep, the floppy cannot
be listed - there is no conventional file system on it.)

Have you done a visual inspection of the motherboard recently ? Are there any
bulging or leaking capacitors on the motherboard ?

http://www.badcaps.net/images/caps/kt7/kt3.html

If I could see some root cause, listed in the postings I can see for Veriton M460,
that would give a better direction to look in. It sounds like it could be
a motherboard issue, but I suspect the machine may have been sold, with more
than one motherboard type installed in it. (Which means, some versions of
the machine might have more problems than others, but the users wouldn't
list the motherboard details for us to know.)

You eliminated the power supply, so that's a start. They're a high runner, in
terms of causing problems.

Failing power supplies, also give little hints about their health. For example,
you may hear a muffled "sizzling" sound at startup. Or see a small puff of smoke
go out the back of the machine at startup. Those are signs of failing (leaking)
capacitors inside the supply. Another indicator I use for my personal machines,
is when I notice a fixed speed 12V fan, is beginning to go "off pitch" on its
fan sound. That can be an indicator of impending failure. It implies the
moment to moment drift of the 12V rail voltage, is larger than it used to
be. I used that to predict the impending failure of my very first supply.
That supply still "works" today, but the output voltage on the 12V rail
drops to 7V, with even a single 0.1 amp cooling fan connected to it.
So now, the supply is as "weak" as is physically possible. It puts out
less power, than a digital camera adapter :-) But technically, the power
supply still works, as under no load, all voltages are present and it's
cooling fan (internal one) still spins. It just can't take any load.
And internally, all the caps are flat, bright and shiny.

Not every failure condition has visual symptoms - but when offered a
visual symptom, go with it.

Paul