BD--
That extra fan is probably your northbridge cooler.
If you hear that chugging at power-up and it eventually settles to the normal din of the fans, then it's probably a worn or dirty fan in your power supply. You may be able to help it out with some Q-tips and alcohol.
Remove the power supply from the case. It should just be held in there with a few screws through the sheet metal chassis.
Open the power supply-- should just be a couple of screws keeping it closed.
Look for a fan. When you spot it, try turning it with a finger. If it feels 'bumpy' throughout its rotation cycle, that's pretty normal. If the bumpiness seems to make it hard to turn with all but the gentlest of nudges, then it's toast.
If it turns freely, use some Q-tips and isopropyl alcohol (I've used scotch in a pinch) to scrub each of the fan-baldes, removing as much crud as possible. Once you have her clean, close the supply and plug it in to see if you've made a difference.
If the fan is clean already, then the bearing(s)-- I use that term loosely regarding the cheapo fans that they put in consumer electronics-- are shot. When a fan spins-up, the motor shaft tends to be pulled toward the impeller due to the suction that the fins generate. When the bearing wears down from this side-load, then you'll get a bit of racket as a warning. That leaves you with two options.
1) Replace the fan-- You may be able to find a similar fan and swap it, but that may require splicing or soldering to connect the DC feed.
2) Replace the power supply-- Bring the old one with you so that you can be certain that the replacement is the same size and wattage, and also that the MB power leads are the same. If you can find a good match, but its output wattage is higher, that'll be okay. If the wattage is lower than your original, that won't be okay.
I've done all three of these options and they're really rather easy, except for the fan replacement one which requires a little splicing skill and some color coordination.
Oh yeah, also check to see if there's any wiring/cables that may be too close to any of the fans also.
Good luck.
-SQ
Edited by: StrangeQuark at: 9/22/04 5:04 am