Let's play "what part is failing?"

[vsp]

This should be simple...

Athlon 1300
256MB RAM
60GB WD HD
not sure on make and model of the case or power supply (local computer company built it for me a couple of years ago)

Lately, the system's seemed to make a bit more noise on startup, as if something was running sluggishly. It'd go away once the system was running for a minute or so.

Tonight, I plug everything in after a weekend absence, hit Power, and the system is on... on... on... shut off after about three seconds, with a blinking light under the light-bulb icon and no other noise or movement. I shut it all the way down, waited a minute, tried it again... same behavior.

On about the eighth attempt, it did finally come on and stay on, which is how I'm typing this now.

It did this once before, a few months ago, but it only "misfired" once.

I would really like to fix this before I _can't_ get it to come back on. First impulse is the power supply -- am I likely wrong?

(Ironically, I have a second fixer-upper right now; I hijacked my niece's malfunctioning Dell 450 with the intentions of wiping the HD and installing a fresh coat of 98SE. I would really love to have at least one functioning computer in the house, though.)

[mbpark]

Heya!

I'd look at the PS first, and then your motherboard second here.

M

[dar512]

Do you have a floppy drive? Try booting from that. It's possible you have a frozen hard drive -- though I haven't seen one of those in years.

[BrianR]

Here's a thought...my computer doesn't want to boot when it's cold. If I warm up the box first, it boots fine. I have no clue what causes it though...maybe a cold solder joint somewhere.

Was your house cold when you tried to turn it back on?

[SteveDallas]

Hmmm. My instinct is, it's not the power supply, or it wouldn't be powering up at all.

It sounds like your motherboard started up, found something it didn't like, and then shut down--something like a CPU fan not working? (It can happen for high temperature as well, but 3 seconds is hardly enough to overheat.)

[vsp]

The apartment was at a normal temperature, around seventy.

If it was an overheating problem, I would think that it wouldn't stay on for any length of time at all. Once this gets over the hump, so to speak, it'll stay on for days. I'd just leave it on and plugged in, but it's thunderstorm season and I'd rather not tempt fate even a little.

If it was a car, I'd get the starter replaced, but computers don't have those (that I know of).

My next step in the meantime is to get some compressed air and clean the hell out of the innards, particularly the fans.

[jaguar]

I can't think of anything Mobo wise that'd make it shut down, usually if the mobo finds something it doesn't like it'll scream at you (series of beeps) that corrospond to which component it's have a bitch over. Full-on shutting down suggests to me a safety tripping in to PS, the fact there was no noises (such as the CPU fan whiring up) increases the chances of that. Unless the heatsink has completely fallen off or something it can't be overheating, if it was it wouldn't stay on anyway.

Most powersupplies are utter pieces of overrated shit made for around $3-4USD (trust me, I worked for an importer), my money is very much on that.

[tw]

The one component that can cause anything inside computer to create the crash is the PSU. PSU is the foundation upon which everything else depends. However only a fool would wildly replace anything only on a whim.

You need two tools - a screwdriver and and a digital multimeter. The second is sold everywhere from Sears, to Home Depot, to Radio Shack. Even though computer fails only intermittently, the bad power supply symptoms exist constantly. You must measure those DC voltages. Those voltages must measure within the upper three-quarters of limits in this chart

Voltage   Wire Color  Min V     Max V 
 +5 V       Red       4.75 V    5.25 V 
 -5 V      White     -4.75 V   -5.25 V 
 +12 V     Yellow     11.4 V    12.6 V 
 -12 V     Blue      -11.4 V   -12.6 V 
 +3.3 V    Orange     3.135 V   3.465 V 
 +5VSB     Purple     4.75      5.25
 !Power On Green      0.8       2.0
 Power OK  Gray       >2.4 when power is good

Once power supply is confirmed by meter, then move on to other suspects.

[Beestie]

Could be an interrupt conflict.

I had one of those once. The video card and something else were fighting over an interrupt and the computer would instantly shut off.

I assume you have tried alternate bootups. Someone above suggested with a floppy - do try that.

Also, try booting up while holding the F4 key. That will dump you into the BIOS config area before the OS cranks up where you can putz with the settings.

Seems that its happening too fast to be an interrupt thing but you never know. Also, consider not turning it off. I never turn mine off.

I also wonder if you have a bad power switch.

[jaguar]

I also wonder if you have a bad power switch.

You may have something there.

[vsp]

Originally posted by Beestie
I assume you have tried alternate bootups. Someone above suggested with a floppy - do try that.

Also, try booting up while holding the F4 key. That will dump you into the BIOS config area before the OS cranks up where you can putz with the settings.

When it quits, the boot cycle doesn't last even remotely long enough for any of that to kick in. It's on -- it's off, maybe two seconds apart.

Also, consider not turning it off. I never turn mine off.

I live in an apartment complex, and do not trust that the building is properly grounded and insulated. I have a surge protector on my system, but do not take it on faith that that would be a 100% effective defense against power surges and lightning. I've lost a couple of modems in my lifetime to such things already, and have no interest in frying anything else; hence, if thunderstorms are likely and I'm not going to be right there to monitor things, it's getting unplugged.

I also wonder if you have a bad power switch.

Possible, but I'm wondering how I test that. I will note that the power switch behaves perfectly when I do the hold-for-five-seconds-to-kill-the-power thing.

[jaguar]

Power switches on modern motherboards are soft, so just unplug the jumpers and touch across the two with a screwdriver (with a wooden or plastic handle).

Really does sound like a PSU issue to me.

In terms of surge protection, I usually use APC gear, kicks ass.

[Undertoad]

Very worst case: the noise is your CPU fan, and it's making noise because the heatsink is uncoupling from the CPU. When the sink is in place the system boots and acts normally. When it's slightly off, the CPU heats up so rapidly that it reaches 80 degrees C in 2 seconds, at which point the mainboard CPU temperature sensor tells the BIOS to shut the whole system down to preserve it. When the sink eventually fails with the system running, it causes a fire which spreads to the papers you've stacked behind the system, and your whole place burns down.

It's probably not the problem, but it *could* be!

[vsp]

Thank you, Tony. Now I will NEVER SLEEP AGAIN anywhere where there's a computer in the house. Yeeeeeegh!

[zippyt]

I hade the same problem once , it was the power supply .

I had a friend that called once asking if i had a spare power supply , his had gone up in flames !!!!!!!!

So go buy a new one , if you have a 250watt get a 300-350watt , the price diff is SMALL !!!!!