Can I fix a non-starting PC?
December 13, 2010 1:56 AM   Subscribe

How do I figure out why my computer won't start?

Please be gentle with me. I know nothing about hardware.

PC (HP Pavillion desktop, only a couple of years old) suddenly failed to start (fan comes on, power light shows, CD drive opens/shuts but no BIOS post, beep or any other sign of life). Replaced the battery and left it disconnected for a bit. Same result.

Left it unplugged for a couple of weeks. Came back to it yesterday, tried it, and now the fan only comes on for a couple of seconds on hitting the power button (and the power light shows, equally briefly, its 'standby' yellow colour, rather than the blue 'on' light). This makes me think it's a power supply issue, but I have no confidence in my judgement on this (see disclaimer above...)

So, dead? Is there anything I can do to diagnose? Is it even worth getting it looked at?
posted by monkey closet to Technology (12 answers total) 2 users marked this as a favorite
Man, that sucks.

0. Is everything plugged in properly? Check the m/b plug, any expansion cards, data and power plugs into drives.

1. Start pulling everything you can. Remove the HDD (both power and data), DVD drive, any expansion cards, basically as bare bones as you can get (just video card and motherboard really). Does that work? (Do you see a picture, it will obv. not boot into windows).

2. If it works, start adding hardware piece by piece, until it doesn't boot anymore, or something had jostled loose, and is now plugged back in properly.

3. If the machine doesn't boot with almost everything out of it, you need to try to boot it with a spare Powersupply, etc.
posted by defcom1 at 2:06 AM on December 13, 2010

uhh m/b plug is the motherboard power plug
posted by defcom1 at 2:07 AM on December 13, 2010


posted by p3on at 2:54 AM on December 13, 2010 [2 favorites]

If you really know nothing about hardware, I would recommend getting someone to look at it. Or get hold of another computer (maybe the one you wrote this question on?) and start searching for guides on how to put together PCs. It's not that hard, but the mass of cables and boards can be intimidating if you have no clue what you're looking at.
posted by bardophile at 2:58 AM on December 13, 2010

It's probably the power supply. Be warned that, if that turns out to be the case, a failing supply can zorch pretty much everything else in the computer. Those failures can be immediate or at some future time, typically within a few weeks, as stressed components fail.

If you replace the supply, and that brings it back up, make an immediate backup of everything you care about. There's no guarantee the computer will keep working. If it starts to get wonky within the next month or so, it may be worth just buying a new computer. You can replace failed components, but on cheap computers, doing more than the supply usually isn't worth the labor, especially when you may have a different part fail shortly thereafter.

defcom is telling you how to troubleshoot properly, which is to simplify the problem as much as you can by removing everything possible, which is typically everything but the motherboard, CPU, RAM, and possibly video card if you don't have one on the motherboard. If it still fails, then try swapping the supply. If a new supply doesn't help, then you're probably best off replacing it, if it was a $500-$750 typical desktop.

Swapping the power supply is a fairly time-consuming process. It's not difficult, but there's a lot of cables to unhook and then hook back up with the new one. Remember that most motherboards these days have TWO power connectors, not just one. Forgetting to plug in the second is a very common mistake.

Taking a few snapshots of the computer before you disconnect anything can help you answer questions during reassembly.

Hopefully, your HP will be ATX standard, letting you use pretty much any supply you'd be able to buy. Verify that before doing anything. I'd look it up, but you didn't tell us your model number.

Size the new one to be at least as big as the old one. Assuming it's a typical family machine, without a separate graphic card, you probably don't actually need much more than 250 watts or so. 430-450 watters are pretty common in brick and mortar stores, and unless your supply is bigger, that should be more than adequate.

Corsair supplies are excellent and usually in most Best Buys. If you want a really topflight unit, and you're willing to wait for shipping, you can order a Seasonic or a PC Power And Cooling online. I generally use But returns would be much harder if it didn't work, so I'd probably just grab a Corsair at Best Buy. If you want something cheap but workable, Antec is cheaper than Corsair, decent, and also available at BB.

If you're really cash-impaired, Sparkle or Fortron (same company, one bought the other) are very cheap, while still built reasonably well. But I think you can only get them online.
posted by Malor at 3:00 AM on December 13, 2010 [1 favorite]

HP and Dell are known for using non-standard ps, look out...
posted by raildr at 3:06 AM on December 13, 2010

no BIOS post, beep or any other sign of life

Last Pavilion I saw do this had a dead mobo.
posted by flabdablet at 7:13 AM on December 13, 2010

2nding dead (or dying) mobo.
posted by WeekendJen at 7:35 AM on December 13, 2010

1. Be prepared to find that the entire computer is dead.

1a. If (1), pull out the hard drive (get help on this if necessary) and save it. When you get a replacement computer, plug in (or have someone else help you plug in) the old hard drive and you ought to be able to recover your files.

1b. If not (1), you'll need to have someone help you figure out what parts are broken. In this case, you need to find someone who is willing to do this as low-cost as possible. Like for instance, I have been known to do a system troubleshoot / repair for a six-pack of something decent. If you have a friend like me, make use of him/her. If not, start making friends with someone who likes tinkering.

2. If not (1) and (1b) fails you, find a computer repair shop. Not Best Buy or the like. Something relatively small and local. Best Buy has a simple troubleshooting guide: A) look at it, B) if it's broken, tell you to you buy another one or C) if it boots but has trouble, wipe the hard drive, reinstall Windows and tell you "Gosh all your files were lost." If your drive is fine, there is NO REASON AT ALL why your files will be lost, except that it is often faster and easier for the repair tech to wipe and reinstall than it is for him/her to actually go in and fix anything. Worst case scenario (assuming the drive itself isn't broken), your installation is screwed, but you should still be able to recover the files themselves by plugging the drive into another computer and copying.

3. Finally, if (1) be happy that this time of year replacement computers are generally on some pretty big discounts. Not fun to have to spend the cash, but it's better than paying more than you need to.
posted by caution live frogs at 9:39 AM on December 13, 2010

Dead motherboard, specifically a problem with the capacitors. (Not the flux capacitors). I had the exact same thing with my Asus motherboard. Good news is, motherboards are fairly cheap.
posted by dougrayrankin at 9:42 AM on December 13, 2010 [1 favorite]

If it is a problem with capacitors on the motherboard, they may look kind of crusty or bubbly, like car batteries. If the little silver-tipped silo-looking things don't look pristine, that's the issue.
posted by santaslittlehelper at 10:33 AM on December 13, 2010

The Pavilion mobo I referred to before died without visible capacitor trouble.
posted by flabdablet at 3:43 PM on December 13, 2010

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