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Connect case fans to mobo or/and PSU? Help please

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August 7, 2009 5:57:13 AM

I have a HAF 922 case, with ASUS P6T mobo. The case have 3 fans, one front 200mm, one top 200mm, and one rear 120mm. But the mobo only have 2 chassis fan connectors, which has Q-fan regulation.

So I am wondering how should I connect the 3 case fans?

1. connect them all to the PSU to rum max speed?
2. buy a fan connect splitter and connect them all to the mobo so they all have Q-fan regulation?
3. connect 2 to mobo and the last one to PSU? then which one should connect to PSU?

I am really confused, Please help me guys, this is my first time build, thanks a lot. :) 
August 7, 2009 12:26:00 PM

Ya, I preffer connecting them to the psu as well. One less thing that the MB has to do and one less electrical thing drawing power from it.
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August 7, 2009 1:42:21 PM

Thanks for your replies.

Then you don't have the mobo regulate the case fan speeds any more.
So do you think that Q-fan function for case fans are just fluffs, not necessary?
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August 7, 2009 4:14:38 PM

As a first step on making this decision, I'd be inclined to say that two of the case fans should be controlled by the mobo through its SYS_FANx ports, and the remaining fan powered by a Molex connector from the PSU, preferably with its own manually-set speed controller (2 or 3 speed levels). Then you monitor typical temps and fan speed on the mobo-controlled units and set a fixed speed on the third one to achieve a good balance point.

Obviously I am disagreeing with the last two posters. I do not think it necessary to run all the fans at full speed all the time, and I do not think it strains the mobo to use its fan control circuitry to do the job it was designed to do. Running fans at lower speed reduces the noise level.

However, you have an interesting wrinkle here. The front fan has its own manual switch (externally accessible) that is on / off only (not variable speed). Moreover, this fan has LED's in its switch (indicator) and on the fan itself to look cool! I do not think you can run that front fan from any supply other than full 12 VDC, and you may well want it running most of the time for the cool appearance of the glowing red fan at the front. So the second part of my initial proposal is not do-able completely. I still think it would be the one to power directly from the Molex off the PSU. But the only options you have for it in terms of control is on or off. That's not bad, of course. If you power the other two from the mobo, they will adjust their speeds to offset whatever the front fan does and maintain proper interior temperatures.

If you really thought my idea of having some speed adjustment possible on the lighted front fan had merit, you might consider figuring out a way to control only the fan's supply voltage without changing the supplies to the switch or fan LED's. That's customization - it is not included in the fan or case design.
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August 7, 2009 6:13:17 PM

I contact the Cooler Master Tech support, they suggest to plug as many fans into mobo as possible, and the rest to psu.

Now the only issue concerns me is noise, I have not put them together yet, but I am afraid it would be too noisy. then I had better change the board to P6T Deluxe. I should have order the Deluxe instead of this one.

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August 14, 2009 12:56:34 AM

I bought a scythe 4-fan controller, to achieve the balance of performance and quietness.

The mobo Q-fan control for chassis fan is too noise, I lower them by 100rpm, the temp of everything remains the same, while it is now much quieter.
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November 3, 2009 6:53:34 PM

hi guys im actually out of space because on my asrock mobo i hace one cpu fan socket and one chasis fan socket, i want to connect my small case fan to my pc how do i connect it thru my psu?
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