Is the problem my PSU or something else on my computer?

April 4, 2006 8:13 PM

Is the problem my PSU or something else on my computer?

The fuse blew one time and one of my hard drives fried, and since the power on my computer flicks out and it restarts itself once in a blue moon. It actually seems to happen more if I'm trying to do a lot on my computer at once with a bunch of windows open.
The thing Im more worried about is that one time I noticed that when I turned my computer on, one of the fans failed to start up.
Would these problems be solved by replacing a possibly damaged PSU, or is it possible that my motherboard is damaged?

posted by who else to Technology (12 answers total)

Yeah, if the power is flickering it's most likely the power-supply, though if it fried a hard drive it's not unthinkable that it got some other important piece of circuitry. Power-supplies are cheap (or free if you work/ know someone who works in a place where they frequently dump old AT cases).

i'd try that first. Also, check the connectors coming off the power-supply, make sure nothing shorted there.
posted by quin at 8:41 PM on April 4, 2006

It's possible that you're right at the limit of the amount of power the supply can produce. If you replace the supply, make sure to get one with a higher power rating.

Generally when a switching supply is overloaded it crowbars for a moment, reducing its output voltage to zero in order to reduce the current flow. Once the power comes back on that will cause the computer to reboot.
posted by Steven C. Den Beste at 8:48 PM on April 4, 2006

Could be both, but I'd start with the PSU. A faulty PSU can take out many other components, but a faulty motherboard will not generally blow up the power supply, especially if you buy a good one.

Antec and Enermax are both reasonably good names that are easy to find... Antec's in most Best Buys. If you're willing to order via the Net, there are many, many good options. Seasonic is apparently a good, albeit expensive brand that's quiet, and PC Power and Cooling is a top-quality, expensive brand that tends to be noisier. (they're super-robust, though.)

If you're still having the problem after that, then you can replace other components. A high-quality good power supply is rarely a waste of money, though, so even if it doesn't directly fix your problem... if you bought a good one, you might want to just keep it.
posted by Malor at 8:48 PM on April 4, 2006

Response by poster: Well, Im running a 5 or 6 year old Dell Dimension 4100 with probably a proprietary PSU. Hmm, maybe these will be cheap, or maybe for 50 bucks more I could just get a new computer...
posted by who else at 8:54 PM on April 4, 2006

If you think there's a problem with your current PSU, I wouldn't recommend replacing it with some beater that's been thrown away (and AT supplies won't work/fit in modern (ATX) computers, anyway).

If you don't have a beastly gaming rig, anything over $40 is probably excessive, or over-priced. Antec's a safe bet, but you can save some money and maybe get a quieter unit by shopping around (newegg has a wide selection, and lots of sutomer reviews).
posted by unmake at 8:58 PM on April 4, 2006

Response by poster: Well the thing I was worried about was if my fan stopped, my computer would overheat and things would die. Is this what would happen or would it just shut off upon overheating?
posted by who else at 9:58 PM on April 4, 2006

seems to happen more if I'm trying to do a lot on my computer at once

The two most common causes of issues under load are both mentioned in your post -- power and heat.

Since heat is easier to test, eliminate it first. Open up your case and blow a desk fan on it, download a program like motherboard monitor to see the temperatures.

If you can rule out heat, then yes, your power regulation is *probably* bad, and a new PSU will *likely* help.
posted by SpookyFish at 10:26 PM on April 4, 2006

Either is a possibility - many contemporary systems shut the machine off (or slow it down) when the CPU's temperature exceeds a set limit. And when the machine shuts down due to overheating, so do the fans, usually, which tends to exacerbate the problem of overheated components.
posted by unmake at 10:31 PM on April 4, 2006

I've been having the exact same problem with my laptop. I thought maybe the power supply had been damaged by surges and was passing them on to the laptop when under heavy loads, which was shutting it down. The battery is in great shape, so it's never really losing power. My apartment has crappy wiring; I have to replace a lightbulb at least every other week. I do have it hooked up to a surge protector.

I haven't checked to see whether or not it happens when I'm running off battery (I haven't actually had to use my laptop away from home this year), which I admit is extraordinarily lazy of me. But, like you, it only seems to happen under heavy loads (the fan is always whizzing when it crashes). It's a fairly beefy 120 Watt power supply.

Sorry if I'm usurping the thread, but any comments on this?
posted by dsword at 10:40 PM on April 4, 2006

Overheating could kill it: my boyfriends video card fried when the fan stopped working. I don't know much about it, but I think you have to specifically set it up to shut down on overheating: it doesn't seem to be a default behaviour.
posted by jacalata at 10:44 PM on April 4, 2006

I agree with the few people above who said it may be heat. You mentioned that one of your fans failed to start up, that would be a cause for the restarting. Especially because you said the restarts tend to happen with multiple windows open (equals higher cpu usage, more heat).

If you were, for example, accessing your hard-drive AND burning a cd or using another device at the same time then that would be reason to look at your PSU.

If you don't want to bother with installing an application, the next time your computer restarts go straight to BIOS and check the on-board temperature sensors (if available). Anything higher than 50 degrees would be highly suspicous. Also while in BIOS you can check the CPU fan speed; sometimes a fan will spin poorly, having the appearance that it is working but not moving enough air to cool the CPU.
posted by Sonic_Molson at 11:15 PM on April 4, 2006

a Dell won't tell you what the temp of the machine is in the BIOS. a 4100 is pretty old - crack open the case and make sure the fans aren't all clogged up and grody. the one problem is that, since it's a Dell, if your (say) CPU fan is all munged up you won't be able to just hit up NewEgg to replace it - Dell's cooling stuff is custom for their machines - and if you have a bad PSU you will definitely need a Dell replacement.

dsword: i'd blame the cooling in the laptop first - those little fans burn out easy. make sure you're not using the computer on your lap or on something fluffy. they need hard surfaces to operate properly. (or, get something like a CoolPad.)
posted by mrg at 7:59 AM on April 5, 2006