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View Full Version : [Question(s)] PC Weirdness, any ideas?



Rudolph
01-06-2009, 08:04 PM
Hi all, thanks for clicking :)

This morning my PC (a ca2004 Dell, PIV 3GHz) started screaming like a jet engine. Took it apart and found the proc cooling fan to be the culprit. After a bit of googling I learned why it had 4 wires, and it kinda sounds like the PWM-ness died and it's running full-tilt all the time.

Here's where it gets odd though. I found a right-sized fan in my box-o-leftovers (amazing!), which is only two wires. Not surprisingly the BIOS complained about processor cooling fan failure. So I plugged in the screamer again, and now the computer won't even POST. Fans turn on when I poke the button, but the little ABCD diagnostic lights on the back do nothing at all, and no activity on the screen either. The Dell owner's manual says no lights is "normal off condition or a possible pre-BIOS failure" and cheerfully suggests plugging it in and pushing the power button.

The power supply is ~8 months old. I checked anyway, near as I can tell (with a multimeter) it's okay. Will possibly prod it some more later.

Swapped vid card for shiggles, not surprisingly there was no difference there.

So my question is this; Anyone have any ideas of what to poke at next? I don't want to write it off as I've no way to replace it right now.

One upside is I now have an LCD for my workbench computer. The other is that the old Dell was a freebie to begin with, the only money I spent on it was replacing the hdd.

Adrenalynn
01-06-2009, 08:40 PM
Did you run that processor with the fan not turning? Only takes a second or two disintegrate that processor, especially the older P4's like that.

Rudolph
01-06-2009, 08:59 PM
Negative. I always had one or the other fan blowing through the heatsink/heatpipe device.

That said, since the fan was apparently dying anyway, it's possible it was under-blowing for an unknown amount of time prior to becoming a screamer. This box lived under an end table next to the couch, and had a different semi-loud fan going in it as well.

Thanks!

Adrenalynn
01-06-2009, 09:40 PM
Yeah, that's possible that it was already getting tired - but it's unusual that it would pick that specific time to finally do the deed as you were working on it...

Rudolph
01-06-2009, 10:31 PM
Agreed, that would be strange :)

Dug deeper, found one swollen capacitor on the mobo, and chunky dry-ish thermal paste under the heatsink. I've no idea if there are any visible signs of a conked P4 or not. Nothing else looks baked. I'll put it back together with new thermal paste, but I'm not expecting anything.

Also found this (http://www.tomshardware.com/forum/51352-2-dell-dimension-8400-wont-boot), seems other folk have had the screaming fan issue, though the dead part varies...

Adrenalynn
01-06-2009, 10:43 PM
I've had many a screamin' fan. Invariably for me it's blown bearings in the fan. I've saved them [until I can get another] by tearing them down, cleaning them out, and packing the bearings in good lithium/teflon suspension lubricant.

lildreamer
01-07-2009, 12:39 PM
Dell motherboards are famous for blown caps- note GX280's and GX 270's - we have over 300 PC's of that model where I work.
as soon as dust gets on the caps, the heat from the processors bakes it and we have a thermal runaway....
unfortunately when you get the jet engine most cases you have to have the mobo replaced - sometimes though you might get away with replacing the fan.
If you got blown caps near memory - you'll end up with corruption with applications and data.
Near the CPU and your system hangs. Sorry to hear about your problem
if its under warranty your fine - if not sorry....

Rudolph
01-07-2009, 02:27 PM
To clarify, the screaming fan isn't bearing noise, it's wind noise.

The fourth wire on the fan is some sort of PWM line (some info (http://www.pavouk.org/hw/fan/en_fan4wire.html)), which allows the motherboard to vary fan speed based off proc load and/or temp. Seems that when these Dells overheat, it kicks the proc fan into "high gear", which then blows like mad. It also seems that by the time this happens it's generally already too late to save the processor. Or something else is cooked that tricked the mobo into thinking the proc was too hot.

Interestingly enough (to me anyway) the fan is labeled "DC 12V 2.50A". I don't think I've ever used a PC fan that was labeled higher than 0.7A before.

Adrenalynn
01-07-2009, 04:32 PM
Yeah, lildreamer's right on. If you have fat bulging caps, you're done for.

Sorry to hear about the death in your family. :( ;)

lildreamer
01-07-2009, 06:16 PM
Yeah, lildreamer's right on. If you have fat bulging caps, you're done for.

Sorry to hear about the death in your family. :( ;)


"Sorry to hear about the death in your family." ??????????????

you might have me confused with some one else - Adrenalynn
My brother suffered a stroke yes, but so far he's still alive its been three months and he lost a total of 100lbs - now he's about 90 lbs and is 6 ' 4"

Adrenalynn
01-07-2009, 06:31 PM
Eeek! Sorry to hear that! I was actually being flip with Rudolph about his computer. It's dead. Death in the "family" Bah. Sorry!