Connecting psu fan to motherboard.

PSUs: The source of DC power for all components in the PC & often a big noise source.

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elijahk33
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Connecting psu fan to motherboard.

Post by elijahk33 » Sun Dec 28, 2014 5:02 am

I'm going to replace the fan of an Antec Neo Eco 400M with a Akasa Apache.
I will connect the fan header to the motherboard and regulate the speed based on system load.
Will the psu work as normal even if there isn't anything connected to its internal fan header?
Do PSUs have protection systems that prevent it from starting if no fan is detected?

Vicotnik
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Re: Connecting psu fan to motherboard.

Post by Vicotnik » Sun Dec 28, 2014 7:15 am

PSUs usually have overheat protection, but no fan detection. It's possible to do as you suggest. Other options are to connect the new fan to the PSU fan controller or directly to to the rails. Your way is best if you want to control the fan. Just don't forget to plug it in. :)

elijahk33
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Re: Connecting psu fan to motherboard.

Post by elijahk33 » Sun Dec 28, 2014 11:36 am

Vicotnik wrote:PSUs usually have overheat protection, but no fan detection. It's possible to do as you suggest. Other options are to connect the new fan to the PSU fan controller or directly to to the rails. Your way is best if you want to control the fan. Just don't forget to plug it in. :)
Thanks for the reply.
I'm quite sure it won't overheat. The Akase Apache fan is known to be quite powerful.
The fan in the Antec psu has never been spinning very fast. I would rate it at less than 1000rpm by hearing it. It actually doesn't increase its rotation speed even under heavy system load. Threshold for increasing fan speed on this PSU is probably at some point after 250W, which is never required by my PC.
I want to change it because it makes some very annoying swishing sounds at regular intervals (about twice a second). System load is pretty low: i7 4770 and R7 260X usually use less than 200W, with rare peaks over 200W.

I have one last question: how do I wire the 4pin fan cable out of the PSU? Can it pass together with the 24pin ATX cable?

MikeC
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Re: Connecting psu fan to motherboard.

Post by MikeC » Sun Dec 28, 2014 3:23 pm

elijahk33 wrote:I want to change it because it makes some very annoying swishing sounds at regular intervals (about twice a second).
Before you do anything else, check to make sure it's not some wire brushing up against the fan blades on the inside.

Vicotnik
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Re: Connecting psu fan to motherboard.

Post by Vicotnik » Mon Dec 29, 2014 4:38 am

elijahk33 wrote:I have one last question: how do I wire the 4pin fan cable out of the PSU? Can it pass together with the 24pin ATX cable?
Sure, that will work. Lots of ways to do it, no need to distance the fan cables from the other power cables. Make sure no sharp metal edge cuts into the cables and you're fine.

elijahk33
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Re: Connecting psu fan to motherboard.

Post by elijahk33 » Mon Dec 29, 2014 7:17 am

I've checked: the fan blades are not touching anything, the noise comes directly from the fan hub.
I'll order the new fan shortly. Maybe first I'm going to run a short test to see if the psu powers up without a fan connected.

elijahk33
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Re: Connecting psu fan to motherboard.

Post by elijahk33 » Fri Jan 09, 2015 12:29 pm

I did it.
I found an unused Cooler Master case fan 1200rpm at home, so I decided to go on and replace the fan for this PSU.
The PSU fan is attached with a small 2-pin conenctor, as expected. I removed it and installed the Cooler Master fan.
I had a small problem: I could not re-use the screws that were on the psu fan because they were way too large. I used some spare screws that came from a Noctua NF-A9x14, and they worked perfectly for the Cooler Master fan.
Second problem: I could not make the fan cable come out together with the other psu cables because there was no space in the hole, which was closed from all ends. Therefore I made the cable pass underneath the fan itself and out of the fan grill, making sure that it doesn't interfere with the fan blades.

The system started up as usual. The new fan is now voltage-controlled by the motherboard, between 700 and 1200rpm depending on cpu load.
The clicking noise vanished. Although the Cooler Master fan is not perfectly silent, its sound profile is far less disturbing.

Vicotnik
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Re: Connecting psu fan to motherboard.

Post by Vicotnik » Fri Jan 09, 2015 1:25 pm

Nice work! :)

elijahk33
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Re: Connecting psu fan to motherboard.

Post by elijahk33 » Sun Jan 11, 2015 8:15 am

Image

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