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new power supply = fans ridiculously louder?

Last response: in Components
October 15, 2006 9:37:38 PM

I just instaleld a new vid card and power supply, and now my fans are blowing very hard and very very loud. My old power supply was an antec 330w truepower, and the new power suplpy is a 600w coolermaster green power. One thing I noticed is the old power supply had a 2 line (blue and black) wire leading to a plug on my mobo labeled case_fan. My new power supply does not have this pair of cables. Is this a variable speed thermostat control or something that would regulate fan speed? If this is the case, then why didnt my fans ever get this loud when I was running it at full load?

Or is it a simple matter of more power getting to these fans? Though I would think the power runnign through those cables would be regulated to give the same output..

What ever the reason, my office now sounds like a wind tunnel =P.

Any Ideas/suggestions?
October 16, 2006 1:09:52 PM

Yes all the fans are louder and blowing harder.

I am running a P4 2.53 on a Asus P4P800 SE Mobo with 2gig of corsair 3200 xms mem. Radeon x850 pro vid, soundblaster Audigy2 zs platinum, in a antec case with 4 80mm antec case fans. Currently not overclocked with stock cooling on cpu.

This is the Power Supply in Question: Coolermaster RS-600-ASAA iGreen Power 600W
October 16, 2006 3:01:57 PM

Check in your BIOS to see if this is enabled:


If so, try adjusting your settings so the fans accelerate faster at a higher temperature.
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October 17, 2006 4:10:21 PM

Depending on the wiring configuration of the PSU fan connector, if its blue and black with no middle wire then its just for monitoring fan speed, iirc.

If there is three wires, say blue, red and black, then the mobo is supplying power to the fan as well,.. which would be odd, considering its already next to the PS circuit board.
October 18, 2006 12:57:00 PM

Lately, I've been seeing power supplies who fan monitor supply a ground wire to the mobo on the same connector.

Since the monitor wire swicthes between NC and GND, i think it may for supplying a better voltage reference for the detector circuit.
October 20, 2006 12:11:00 PM


I used to have an Antec power supply with the same blue and black cable.
The PSU also had a couple of molex connecters which were labeled "fan only".

What happens as far as I can see it, is that when you have the blue n black cable connected to your motherboard and fans connected to the fan only molexs, the PSU controls the speed of the case fans, so presumably this is the reason why your fans run faster with the new PSU.

I know this isn't exactly the same PSU as you had but if you look at the 10th item in the features list, it mentions this fan control.

HTH :) 
October 20, 2006 12:28:43 PM

Thats what I believe, that 2 pin connector is most likely to control fan power from molex and probably the PSU's fan also. Now that you disconnected it, your mobo (if your using 3 pin headers for fans) or PSU is supplying full voltage to every fan in your case even if its not needed.

Get a fan controller, or some 12V-7V adapters.
October 20, 2006 12:56:22 PM

Sounds like your computer is no longer being massivly under powered ;)