I have recently had a problem with my computer. Last week I took the system apart for cleaning (it was mighty dusty in there). After I reassembled everything, I had no immediate problems. I just couldn't get the green power LED on the front of the case to light, even though I had hooked the leads back up to the mobo. Two days later, I installed a new video card, and the HDD LED also stopped working. The next day, I installed a Zalman fan over my processor. When I plugged everything back in, I smelled something burning, and the mobo's power LED flickered on and off. I unplugged everything, uninstalled the fan, reinstalled the old one and now the system turned on, then immediately turned itself back off and wouldn't restart. I reset the bios via battery removal, yanked out the board/cpu, hooked it up w/a different power supply and got the system to turn on by shorting the pins with a screwdriver after about 45 min of fiddling. It posted, so I shorted it again to turn it off. When I tried to restart it again, by shorting, it wouldn't work. I've since switched out the video card and have only gotten the machine to turn on one other time. Is this a sign that my motherboard has gone to that great parts bin in the sky? Or is this some other problem?
Any help/opinions would be very much appreciated.

I'm sorry to tell you, but I think you fried your MOBO.
Something was probably damaged in the powersupply onboard which could be the reason that your leds stopped working.
After installing the new fan (which uses more current then your old one) you probably burned a few capacitors (or tracks)or something.
Capacitors *can* be replaced but I don't think it's worth the time/effort.
Look at your MOBO and see if you can find some leaking capacitors. (brown stuff coming out of the top/bottom)

Look at your MOBO and see if you can find some leaking capacitors. (brown stuff coming out of the top/bottom)

Capacitors don't have to leak, in order to be dead. Their tops should be flat, and if you see a capacitor that looks like it's top is round, sticking upwards (damn, my english really sucks), then it's just as dead a a leaking one. On the whole, dead capacitors don't cause the MB to just not work, they cause all sorts of werd bugs, while on the whole the system does work.

BTW, cool signature :) Deep Purple is one of my faves as well :)

After installing the new fan (which uses more current then your old one) you probably burned a few capacitors (or tracks)or something.
Capacitors *can* be replaced but I don't think it's worth the time/effort.
Look at your MOBO and see if you can find some leaking capacitors. (brown stuff coming out of the top/bottom)

Regards Niek

Crap. I figured as much, but I wanted to get a second (third, fourth) opinion on it. None of my capacitators look out of the ordinary, but the board sure isn't working.

Is there any way I can guard against doing this again in the future? How can I know if a fan will suck too much juice through the mobo? Is that what the additional power connector on the board is for? Or is that completely unrelated?

Thanks for all your help

keeping the mobo alive is easy - get a ups and a good strong psu.

Capacitors don't have to leak, in order to be dead.

I know, but IF they leak, they are definitly dead :)

they cause all sorts of werd bugs,

That's why I thought of them when the OP mentioned the leds going dead one at a time, and that the computer sometimes started and sometimes didn't.

How can I know if a fan will suck too much juice through the mobo? Is that what the additional power connector on the board is for?

Normally this wouldn't be an issue, but because your mobo probably was damaged (one way or he other) it became an issue.

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