Rebooted and my computer won't boot up.

#51

On Sun, 20 May 2007 10:41:55 +1000, Franc Zabkar
<fzabkar (AT) iinternode (DOT) on.net> wrote:

Quote:

On Tue, 15 May 2007 21:28:29 -0700, Ant <ANTant (AT) zimage (DOT) com> put finger
to keyboard and composed:

How do you rate it compared to Antec (had two died in recent years),
Enlight (had them die like five years ago), and SeaSonic (have a 600 watts).

My computer history at
http://alpha.zimage.com/~ant/antfarm/about/toys.html said for PSU incidents:

Don't remember before. Probably replaced PSUs due to weak powers and/or
noisy fans?

I'm wondering just how "weak" a PSU has to be before it has an impact
on stability.

Depends on where it's weak?
If they overrated the current capability it may fail to
start the system at all. It might crash under heavy load.
It might just squeak by until some of the capacitors start
going out. This latter situation is one I commonly see,
people begin to see new error instances and finding no
OS/software fault.

Quote:

I say this because I'm currently working on an Athlon XP 2000+ box
that suffers from hangs and POST failures when cold. Once it warms up
it passes torture tests all day.

Hard to say, you could substitute another PSU to see if that
resolves it, though if it were something a bit more
difficult to find like a cold solder joint, crack in a
board, mechanical connector or even a tin whisker, it could
be intermittent based on temp.

Another alternative would be to heat up the system with a
heat gun or hair dryer/etc, then try to start it.

Quote:

During the course of troubleshooting, I replaced six GSC branded
2200uF 6.3V caps in the Vcore regulator on a Soltek motherboard. Three
were swollen but the rest looked OK. All tested fine using an ESR
meter. It seems that the motherboard must have been designed with
plenty of margin because these caps do not appear to have been the
cause of the problems (the symptoms are still there after replacing
them with Rubycon ZL caps).

Perhaps not the problem "yet", but given they were swollen
it was only a matter of time.

Quote:

Furthermore, the design of the Ritmo branded 350W PSU is such that it
regulates by maintaining a weighted average of the +5V and +12V rails.
When subjected to CPUBurn's torture test, the voltages sensed by the
IT8705F hardware monitor IC are +4.61V and +12.65V. On light loads,
with CPUIdle cooling the CPU, the voltages are +4.96V and +11.81V. The
voltages at the PSU, as measured via an unused HD connector, are +4.95
and +11.88 at idle, and +4.85 and +12.68 when heavily loaded.

It appears as though the PSU has insufficient 5V current
capability.

Quote:

The motherboard (SL-75DRV4) uses +5V to power the CPU, hence the
reason for the sag under load, but I find it surprising that there are
no adverse effects when the volts drop to +4.6. It seems that a PSU
has to very bad for this motherboard to misbehave.

Wouldn't a failure to post cold be an adverse effect?

I tend to agree though that a PSU can be fairly poor and
still run a system, for awhile, except that doing so puts
enough stress on the PSU that it then fails in some way like
it's caps venting, which then will effect stability in a
matter of time.

Also consider the parts like chipset are not using 5V rail
directly so with the additional layer of regulation it
affords more margin. It might be a bit more difficult to
test other components using 5V rail though, seldom do you
find diagnostic programs for random PC, PCI cards, for
example.

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Rebooted and my computer won't boot up.

Re: Rebooted and my computer won't boot up. - 05-19-2007 , 08:51 PM