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Possible Duplicate:
Buying A Computer “Case” Fan… Does It Always Run At 100% Unless Told Otherwise?

I don't have quite enough 3 pin fan slots on my Motherboard so I'll need to run at least one on Molex. I don't have a fan controller, so are these fans on molex going to always be running at max speed due to no PWM and no voltage controller? If I put them on Molex I'm no longer able to measure the fans speeds so I'm not sure, but if the fans are going to run at max speed I'll need to run some of the quieter fans on Molex

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marked as duplicate by Journeyman Geek, Bob, Dennis, Ben Brocka, bwDraco Dec 30 '12 at 21:11

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Um, how is this "not constructive"? It's a matter of fact, as proven by the answer. "How fast" is not "how many RPM will these different max RPM fans run on average" or something non-quantifiable, if you read the question it's simply "will they run at max speed or not" which is perfectly answerable by fact. – Ben Brocka Dec 30 '12 at 12:23
Yeah, I've reopened the question. I had the tab opened because I knew it was going to become a victim of the review queue and people voting to close without properly evaluating the question. – slhck Dec 30 '12 at 14:12
up vote 6 down vote accepted

Yes, on molex they will run at 12volts witch is the maximum of a normal desktop fan (producing the maximum speed).

If you think that it is too loud, then buy one of these resistances: enter image description here

You can easly find them at almost any computer parts store.

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Are they tunable or do they just step down the voltage? – TheLQ Dec 29 '12 at 20:42
They reduce the voltage. To be able to change you must get a fan controller. – Cláudio Pereira Dec 30 '12 at 1:13
@TheLQ Fan controllers typically just have variable resistors (usually a potentiometer) somewhere accessible, e.g. on the front panel. Smarter ones may even have built in temperature monitors and circuitry to automatically adjust fan speeds. – Bob Dec 30 '12 at 14:26
You can, of course, make your own resistor cable, or modify an existing one with different-sized resistors. – Daniel R Hicks Dec 30 '12 at 14:28

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