On 14 Feb 99, at 0:26, Wendy Brown wrote:

> John,
> I bought a new mobo tonight and after putting everything together
> again - nothing happened - just as if there was no power.  Then my
> son thought about the problem with the previous hdd that I replaced
> in November and we disconnected the hdd - it turned on this time.
> What is causing this problem with my hdds?  Is it possible that a bad
> pwr supply could cause the hdd to short out?  This is the same thing
> that happened with my last hdd.  Have you ever heard of this
> happening before?   Have you heard of problems with this particular
> WD (5.1) ?  Do you think that WD would replace either of these
> drives?  They are both less than 2 years old.

  I have a WD 5.1 that has served faithfully, and I'd hate to begin to
suspect it.

  A system that doesn't boot when everything is plugged in, but boots
okay when some devices are disconnected sounds very much like a
possible power-supply problem.  The only time I've seen a drive "short
out", it had nothing to do with the PS.

  I very much like John Chin's suggestion that you install a UPS.  A
good one will not only carry you over short power outages, but also
"condition" the incoming power, moderating spikes and attempting to
compensate for brownouts.

  A normal household circuit is generally rated about 15a; commercial
circuits are typically rated at 20a.  A hefty PC needs something in the
neighborhood of 4a, so unless you have several major appliances on the
circuit as well, a few strings of Christmas lights shouldn't have a
noticable impact....
  One possible source of "surging noise" is the power-supply fan
bearing.  If that stops, heat produced as 120v AC is turned into 5v and
12v DC builds up inside the power supply, and this is one way to
(eventually) get flames to shoot out of it.
  The 5v supplied to the motherboard gets regulated down to 3.3v, and
even lower if an MMX CPU is used.  Rectifier components are usually
fitted with heatsinks -- that wasn't enough to save a few I've worked
with from exploding.  Luckily, *you* get a boot if the HD isn't
connected, indicating that this is not your problem.

  Particularly if you have been upgrading, the power supply in your
case may not be quite hefty enough for your current mix of peripherals.
It it's rated for 250w or 275w, consider a 300w or 350w supply.

David G

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