[SOLVED] Asus p5q se/r 3 pin fan control.

[clarkey1984]

Hi all, I've just bought the above board 2nd hand, everything works great, apart from my case fans, now, I'm unsure as to whether 3 pin fans are true pwm units or not, but the setup with my old intel board was my 2 rear 3 pin case fans (exhaust) off the rear chassis header using a 2 way splitter, and my front and top 3 pin fans (inlet) off the front chassis header using an identical splitter.

however, this Asus board has one header marked chassis fan near the rear of the board, and another identical header labeled power fan slightly further over and lower down near the pcie slot, the rear ones that are connected to the chassis one behave normally, but the pair connected to the power fan header just go flat out regardless of what I tell qfan or anything else in the bios to do, speedfan also doesn't do anything to help me.

To me the logical thing would be to get another splitter and just run all 4 from the chassis header, is 4 80mm fans ok off a single header or would it be too much load?

Many thanks in advance

 

[william p]

3 pin fans are not PWM. The 3rd wire is an RPM sensor. There were some 3 pin fans with thermal speed control that sensed air temperature and if used on the back of a cooler would self regulate.
Nydec M35105-57 was one. But at 1.8A. not all MB can support it. There are others.
The -57 on the end means it's thermal control.

 

[william p]

Here's a new one.
https://www.moddiy.com/products/Nidec-Beta-V-TA350DC-M35105%2d57-9CM-12V-9038-Fan.html
They can be found in old Dell Dimensions for scrap prices. It's also 38mm thick.
It's old tech so hard to find but they exist.

 

[clarkey1984]

Oh I see, the setup in my case previously was 2 3 pin fans from the rear chassis header, and another 2 3 pin ones from the front chassis header, but with this Asus board i only have the one chassis header, the fans are all identical and are controllable, presumably by variable voltage on one of the wires, because if I have a swap around and connect the other pair to the cha fan header instead then they work as expected, although I think I've managed to answer my own question, as after a little research I've seen that the pwr fan header is designed for monitoring the PSU fan speed, if the PSU has the associated connector of course, and as such isn't controllable like the rear one is.

 

[clarkey1984]

I grabbed some splitters like I said and everything is working as intended, on a related note, owing to the massive alaska cooler and it being a P5 board, I'm running a modest 20 percent overclock, set the fsb to 400 (333 as standard) with everything else on auto, 3.6ghz all day long and the CPU temp has never passed 64 degrees, even after running prime95 and gaming for hours, very happy with it, it seems there's still some life to be had from LGA 775.