Geek pop quiz!

[theweaselking]

Computer worked just fine four months ago. Then it was unplugged. Now it's plugged back in and won't boot. Won't even POST most of the time, and when it does POST, it never proceeds past that. No output from any of the video outs, regardless.

Dead CMOS battery?

Any other possibility?

UPDATE: It's a bad power supply. Take out enough of the drains (for example, unplug all but one stick of RAM, the video card, and the motherboard) and it consistently boots long enough to tell me that there's no keyboard and no HDD, press F1 to continue.

And it doesn't matter *which* stick of RAM I leave. So it's not RAM.

I don't have a spare known good PS[1], so I'll take it to The Local Shoppe tomorrow to use their spare.


[1]: I have two known good PSen. One drives my wife's computer and she will kill me if I touch it. One drives *my baby* and I will kill me if I touch it. So I have no spare known goods.

Comments

[catsidhe.livejournal.com]

Electrolytic capacitors can decay, especially if they are not used for a while. Look on the motherboard and in the power supply for caps which are bulging or leaking.

It also depends on the model. There was the Great Capacitor Plague a couple of years ago, which meant that every Dell Optiplex GX270 we saw was guaranteed to need a replacement Mobo: all you had to do was call the helldesk and say "GX270: bulging caps", and they'd send out a tech, no further questions asked.

The Plague may have affected this PC as well, if it's old enough.

[paoconnell.livejournal.com]

Bad electrolytic capacitors are the most likely culprit (or maybe the power supply).

Bad CMOS battery is a cheap fix if it's designed to be replaced. Many aren't.

Laptops are not normally designed to be repaired even by someone who has some idea what he/she's doing, unless you have the normally unobtainable manual and access to expensive parts. You can replace memory cards or hard disks, however.

If it's a tower or minitower, try carefully cleaning out the dust inside the tower, re-seat all boards and any loose connectors, make sure the disk cables are secure (including the little extra one in some PCs).

Close up the tower. Connect the keyboard. Plug in the power cord.

Then turn on the switch again.

If it works, good.

If not, resign yourself to going to the repair shop or buying a new PC.

[theweaselking.livejournal.com]

I never buy new PCs when the old ones still have decent specs, unless I'm purchasing a toy.

And, since *my baby* is still working absolutely perfectly (redundant hot-swappable power supplies! Terabyte RAID-5! Multiple graphics cards! In a DESKTOP! I LOVE IT!), my old machine is totally just getting a new power supply tomorrow, given that the problem appears now to clearly be a bad PS.

[dilickjm.livejournal.com]

Dead video is a likely culprit as well. RAM a possibility. When you say "It won't POST", do you mean no beeps, no output, or what?

If you have a dead CMOS battery, you'd still have video output, it would simply force you to set your CMOS on power-up, so I don't think that's it.

If it's non-integrated video, I'd try reseating the video card as a first step, followed by tossing another card in another slot as a second (this is why I keep an ancient PCI video card here).

[theweaselking.livejournal.com]

"no POST" means no beeps.
"POSTs sometimes" means it gives out the one good beep, but doesn't go past that.

[catsidhe.livejournal.com]

Sounds like a dodgy power supply which can be caused by the power supply itself being busted, by the power bus filter caps on the motherboard being busted, or, and I have also seen this, by a component shorting a power line to ground.

Check all electrolytic caps you can see for bulges and/or leaks. If you see any, there's your primary suspect.

Unplug all components from the power supply except the mobo (disks, mainly), and all cards you can from the mobo. See if it still fails. (Try the RAM too... if it is preventing the POST, then in the absence of RAM you'll get a consistent POST RAM fail.) If it works, plug things back in one-by-one until you find the one that is screwing the pooch.

Otherwise, disconnect the power supply from everything, and put a multimeter on the supplies: make sure that +12v is +12v, +5, +3.3, &c. If it is, that doesn't necessarily mean it's not broken, it might not be able to supply the draw any more.

Try a spare P/S on the motherboard, see if that works. If it does, it's the P/S, if not, it's the mobo.

Bon chance.

[theweaselking.livejournal.com]

Definitely bad PS. Unplug enough devices, *regardless* of which devices they are, and it boots. Well, it boots long enough to say it's got no hard disks or CD drive or power, but you know what I mean.

[ronebofh.livejournal.com]

Dodgy power supply. Bad motherboard.

[theweaselking.livejournal.com]

Why would those have gone bad during the downtime? Just bad luck?

[ronebofh.livejournal.com]

Both have happened to me in the circumstances you've provided, yup. I even had one box come up, issue an error message "Motherboard failure", but boot anyway; i updated its BIOS, rebooted, and it never came back (not even power).

[theweaselking.livejournal.com]

Definitely bad PS. Unplug enough devices, *regardless* of which devices they are, and it boots. Well, it boots long enough to say it's got no hard disks or CD drive or power, but you know what I mean.

Well, first I need to know

[skippy-fluff.livejournal.com]

did it have any political yard signs up during the time it was powered off?

Re: Well, first I need to know

[paoconnell.livejournal.com]

Silly skippy_fluff! PCs don't have brake lines to cut.

More seriously--why are Canadians being suddenly being afflicted with evil and potentially fatal sabotage like the brake lines? In the US at least, that sabotage is a felony.

Re: Well, first I need to know

[theweaselking.livejournal.com]

There's no such thing as a "felony" in Canada, but we have an equivalent class of crime.

And yes, this is that. Reckless endangerment, possibly even attempted murder, as well as all the vandalism charges.

[scifantasy.livejournal.com]

Shoot the computer.

(Fish, barrel, &c.)