[SORTA SOLVED:] Re: recover from a bad F16 install

[Tim]

On Tue, 2012-03-20 at 12:59 -0700, Paul Allen Newell wrote:
> I hadn't thought of the power supply as I assumed that if that were
> the problem, everything would go down rather than selective components
> as it got worse and worse.

If a power supply is sagging, other things may have started working,
*then* a drive may try starting up, afterwards.  This changes the load
on the power supply, and the output from a failing power supply may drop
(voltage go down, as it's less able to supply current).

Hard drives do some self tests as they start up, and may abort working,
all by themselves.  Various bits of hardware are quite dumb, and simply
do what they can when power is applied.  They may error, at some time,
if the power supply goes really bad.  But if the supply is marginal, it
may be good enough for some things, but not for other things.  It can
also be that a power supply is good enough to run the drive, but not
good enough for getting it to start up.  So the drive may start
sometimes, but not others.

Marginally good supplies are one of those things that can be hard to
measure, if you're just going to poke around with a voltmeter, not
really knowing much about what you're doing.  The meter can show the
average, or steady-state, voltages, which may be okay readings.  It's a
bit harder to see how things go momentarily bad, when a drive tries to
start up.

Of course, some users may not attribute things occasionally failing to
being any particular fault.  e.g. The average Windows user are used to
the system randomly doing stupid things, and do nothing about trying to
fix the problem, thinking that, "computers are just like that."

Power supplies need to be able to supply more watts than the
steady-state demand of a running system (that's if you even know what
the requirements of the parts are, most don't list them, so you may have
to make guesses - there are on-line calculators for estimating this).
They need to be able supply more than the average requirement of the
hardware, so the supply isn't always working hard to produce the normal
amount of power to run the hardware, and to account for the turn-on
current (which is higher).  On the other hand, putting a 500 watt supply
into a computer that only needs 150 watts is a bit ridiculous, and a
waste of money.

> Took a look on eBay and pwoer supplies and certainly cheaper than
> motherboards --- I'm seeing $60-$90 range. I can see a whole lot of
> xw8000 stuff and it doesn't look like any of them have a bid.

It can be hard to justify buying parts for a system you don't think is
worth maintaining, but it's handy to accumulate spare bits and pieces.
You probably will want to fault-find something, at some stage, or for a
friend.  On that note, you don't have to get a spare power supply, you
could unplug one from some other computer, try it out, then put it back
in.  Or, it may be the easier solution to unplug the hard drive and try
that out on another computer.  And, as another message brought up, you
may be able to temporarily remove one or two thing in your computer, to
reduce the load on the power supply.  Though, if it works, it does point
a finger at the power supply.  But, if the fault doesn't clear, you
could still have a power supply problem.  It depends on whether what you
removed reduced the load on the supply sufficiently to make a
significant difference.

I'm lucky, in one sense, that people tend to give me old bits of
electronic junk, knowing that I work in that field, and I get to
accumulate some spares.  On the other hand, I often get given stuff
that's complete junk, and have to find space for it, or ditch it.  ;-)

-- 
[tim at localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

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