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This is an HP Pavilion 533w running Windows XP. According to the owner, it's been working fine since 2002 (yeah, it's pretty old, but I'd like to fix it if I can). Then, just recently, it started shutting off a few minutes after being turned on. I opened it up and noticed that when it shuts off, only some components stop working. For example, the power supply fan continues to spin, but the case fan and the processor heatsink fan stops. The power LED on the front turns off, but the hard drive indicator lights up continuously. In addition, the hard drive continues spinning. If I hold the power button down, everything will power off completely.

I suspected it might be overheating, so I let it idle for a while at the BIOS screen, but the temperature stayed steady at 38°C. Then I popped in the Ultimate Boot CD and ran some stress tests, but it worked fine. Then, I thought it might be a problem with the power supply itself; maybe it would stop supplying power to some of the cables, so I tried a power supply that I know works, but that didn't help.

When Windows boots, it wants to run chkdsk, which I allow it to do. It finds a few problems, corrects them, and then the system powers off at around the end of step 2 or the middle of step 3. If I skip chkdsk, I can get to the desktop, but then the system shuts off between 3 and 5 minutes later. This made me think it might be a problem with the hard disk, so I ran MHDD32, but it reported no problems. I then booted a Windows XP Recovery CD and ran chkdsk from it, but it finished without problems.

At this point, I'm back to thinking it's a heat issue, but I'm not sure where to go from here. Does anyone have any suggestions?

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2 Answers

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Turns out 10 of the 1500μF capacitors on the motherboard were bad. Should be easy to replace.

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Would like to hear stories of success re capacitors. I have an ailing mobo that I might want to try the same trick with. – Rolnik Nov 8 '10 at 4:41
It worked fine. I ordered replacements from BadCaps.net. It took me about 2 days to practice on an old motherboard I had lying around, because it was my first time soldering electronic components. But once I got the hang of it, the whole process only took 30 minutes or so. You'll need a soldering station (preferably with adjustable temperature, because in my case, the old solder melted at 450 degrees, while the new solder melted at 375), solder sucker, 0.22" rosin-core solder, and isopropyl alcohol to clean the contacts. – David Brown Nov 8 '10 at 15:29
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75% chance you have a broken or underpowered power supply. Have you added any new hardware lately? Shoot, it could be you added something 2 years ago that put the PC 'on the edge'. Anyway, any departure from the 'stock' configuration could call on the PSU for more power -- which it can't deliver.

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According to the owner and what I've checked on HP's website, everything is original. The current power supply is 200W, while the one I put in as a test was 400W. But the symptoms didn't change. – David Brown Oct 14 '10 at 20:06
OK,probably not heat & probably not a bad PSU. My next guess is a short circuit somewhere. Is it possible that either a screw has come loose, or some metal filing has been liberated from a the case and landed in one of the circuits? – Rolnik Oct 14 '10 at 20:21
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In general, the same 'spring cleaning' that loosens up dust bunnies might help with some stray pieces of metal. – Rolnik Oct 14 '10 at 20:22
Try another hard drive. – Moab Oct 14 '10 at 21:42
Tell me more about – Rolnik Oct 14 '10 at 21:49
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