I have a Dell Dimension 4300. Every morning I come and push the
power-on button and it starts right up. Almost always. A couple of
times now I push the power-on button and nothing happens. So I push it
again. And again. Nothing. A few minutes later it starts up all by
itself.

That's happened twice. The first time, I opened it up and blew the
dust out of it with the vacuum cleaner. There was a lot of dust, maybe
four years' worth. When I got it pretty clean I tried the power-on
button again and nothing happens. I'm thinking I'm going to spend the
day measuring power supply voltages, and while I'm standing there
looking at it, it starts up, all by itself.

It starts up fine for the next few days, and today again there's no
response to the power-on button. I press it again a few times, and
again nothing. I'm thinking it's more than dust causing this problem.
A few minutes later it starts up, again all by itself.

Any suggestions as to what's causing this would be much appreciated.

On May 1, 10:09 pm, dogbreath <mr.mxyzp...@att.net> wrote:
Check the main on/off connection on the m'board. (remove & replace
terminal)

On 1 May, 22:09, dogbreath <mr.mxyzp...@att.net> wrote:
Power supply . They can be blamed for 99% of all stop start problems .
I always keep a spare handy for checking issues out

"Bluesplayer" <bluesplayer59@yahoo.co.uk> wrote in message
news:fcbe3f55-a67a-40ff-b8c0-a94d2362ec8a@z72g2000hsb.googlegroups.com...
(I agree with power supply BUT if money more important than time, to
narrow it down first ...)
Since it did "start on its own", I'd assume flaky/dirty/sticky power-on
switch, so "a few minutes AFTER pressing" it the weak spring FINALLY
pushes hard enough to make the contacts. To test: rather than SHUTDOWN at
night, choose STANDBY . In BIOS set POWER so that pressing the spacebar
can 'power on'. End of day - standby, next morning hit the spacebar. If it
sometimes fails too , then NOT the power button. BUT if that ALWAYS
works - you learned something about the problem -fine. Then still choose
STANDBY at night and in the AM press the power button. If that is still
flaky, then the only variable is the button.

Did you also spend time blowing out the powersupply itself?
It collects a serious dust bunny population all by it self.

- Bobb - wrote:

"dogbreath" <mr.mxyzptlk@att.net> wrote in message
news:95ck14p2c4kspojb6113454qtmu3reac43@4ax.com...
my old p4 system (asus p4t533-c) based system did exactly what you are
describing...
for me it was the cmos battery.

Cleaning is important. but might want to try a battery as a first replaced
component.

battery is definitely cheaper than a powersupply.

dennis

On 2 May, 14:26, "dennis meissner" <j...@4fun.com> wrote:
I find that hard to believe.

I think when the CMOS battery is low, the clocks slows. But when it is
out, the computer still Always turns on. The computer beeps, and the
BIOS resets.. and you can still get to the BIOS.

Similarly, the guy that thought dust in the PSU would stop the
computer turning on. Nonsense.

And he should not be cleaning his computer with a vacuum cleaner!!
Doing that is a joke!

There are air canisters - they blow. A vacuum cleaner is a bit
aggressive, it may even create static..

"dennis meissner" <just@4fun.com> wrote in message
news:JEESj.13$JG5.0@newsfe07.lga...
If CMOS battery , wouldn't it ( didn't it) prompt you at power on with
BIOS screen ? Rather than 'normal boot'.

dogbreath wrote:

I would just replace the PSU.

--
Best Regards:
Baron.

"- Bobb -" <bobb@noemail.123> wrote in message
news:04KdnWEDju-2hobVnZ2dnUVZ_qCunZ2d@comcast.com...
experience. Once
I replaced the cmos battery the system powered up each time as normal....
every time!

Dennis

On 2 May, 22:49, "dennis meissner" <j...@4fun.com> wrote:
The battery has nothing to do with the power supply , it just stores
your clock and bios pre sets . Like pushing off a diesal car , once
the motor spins its away all day .

On Thu, 1 May 2008 14:26:21 -0700 (PDT), sandy58
<aleckie60@googlemail.com> wrote:

Good idea. I'll try that next time. I don't think that's it, but it's
easy to try.

Thanx.

On Fri, 02 May 2008 02:04:27 GMT, Hp <Nope@nana.net> wrote:

I agree with Bluesplayer that it's probably something in the PSU.
Switching-mode power supplies are mostly magic. But I like Bobb's
suggestion of trying STANDBY mode instead of SHUTDOWN as a diagnostic
tool. And I ain't sure I want to keep a Dell PSU on the shelf for the
next ten years "just in case".

It's a good diagnostic trick, though. Eliminates the power-on switch
and the connection to the mboard.

Actually, I think it's a momentary contact switch. The spring doesn't
make the connection, it breaks it. And I think the connection doesn't
even have to break after it's been made. Just making the connection
should start things up.

On Fri, 2 May 2008 14:49:39 -0700, "dennis meissner" <just@4fun.com>
wrote:


Trouble is, you don't really know if replacing the cmos battery is
what fixed it. Maybe it just needed to be powered down and rested for
a while.

Maybe an electrical glitch jolted some part of the startup logic
circuitry into an illegal state, and all you had to do was pull the
plug and let it leak off and settle down, and then it would be fine.

On Fri, 02 May 2008 22:30:38 +0100, Baron
<baron.nospam@linuxmainiac.nospam.net> wrote:

Sure, but then if the problem goes away, did that "fix" it? I still
won't know what the problem actually was.

On Thu, 01 May 2008 14:09:21 -0700, dogbreath <mr.mxyzptlk@att.net>
wrote:

I really, really appreciate all the responses I've gotten to this
question. I like Bobb's STANDBY diagnostic tool best, and will surely
try it. Nobody gives a good reason for the delayed, "all-by-itself"
startup, but several suggest a flakey PSU. Switching-mode PSUs are
electronic alchemy, and something in their magic could explain a delay
in their output voltage buildup. Or maybe not.

On Fri, 2 May 2008 06:44:47 -0700 (PDT), "jameshanley39@yahoo.co.uk"
<jameshanley39@yahoo.co.uk> wrote:

You're right. It's the same vacuum cleaner I use to clean my bird's
cage. Just connect the hose to the other end. Haw haw.

I have a canister of Blow-Off that I use for my keyboards and
photographic film. I'll just get me some more of that and schedule me
some regular computer blow-off days. That's a good idea.

Thanks, jameshanley39.

"dogbreath" <mr.mxyzptlk@att.net> wrote in message
news:l5fn14h21nd3q5rdng24ov1ksdbj225fsk@4ax.com...
but after changing out the battery I had no further problems for the last 6
months.

It was pretty solid in not powering on immediately when hitting the button.
After the
battery replacement it was fine... not saying this will fix the op's
problem... just as
mentioned earlier "my experience".

a battery is cheaper than a powersupply.

-dm

In article <9hfn14hkh6iogmaqj23io5gj33cb4jsgbg@4ax.com>, dogbreath
<mr.mxyzptlk@att.net> scribeth thus
Well it'll sure be the power supply next time;!..
--
Tony Sayer

In article <c1gn14tunb9nrpp2rom1curokd43entj66@4ax.com>, dogbreath
<mr.mxyzptlk@att.net> scribeth thus
Alchemy is not a bad word, turning base crap metal into power;!..

Seriously the one bit of the PC that could always do with an upgrade to
something better and usually quieter.

A quiet PC is like a good quiet woman .. rather desirable to live
with.....
--
Tony Sayer