Pwm and 3 pin fans on akasa splitter.

setter · 24 Jul 2012 at 15:08

Been running my Alpenfohn k2 cooler fans via a 3 pin akasa PWM splitter cable. Upon installing 2x xilence red wing 1400 rpm 3 pin fans in my case roof, i didnt have enough fan headers on my board and my fan controller is borked. So i had a spare akasa 5 fan PWM splitter, i connected the 2 PWM cooler fans to this, then added the 2x 3 pin xilence fans. Now the cooler fans seem to be running full speed all the time. Previously they would ramp up and down according to how they were calibrated in asus ai suite. Or is this a case of the board now just recognising the 3 pin fans as being connected to the cpu header, as basically the splitter cable is acting like an extension. This board, (asus p6t dlx v2 x58) like most modern asus boards cant speed control 3 pin fans.

BrianB · 24 Jul 2012 at 15:46

Hm, have you tried it with just the PWM fans connected? Maybe it can't work with 3 non PWM fans connected? No idea what the motherboard will think of the RPM reading it gets lol.

setter · 24 Jul 2012 at 15:53

Yep, until a few days ago the splitter was just being used to control 2x PWM fans on the cooler. I can only assume that the board is seeing the 3 pin fans now as the cpu fan. Hence the readings of 1400 rpm, the fastest fan on the cooler is 1500 rpm. Once i get a new fan controller ill be moving the redwings over to it.

Tealc · 24 Jul 2012 at 16:02

Maybe you've got it wired up in a strange way or something as its unlikely the motherboard will be intelligent enough to detect which fans you've got connected, especially with a splitter. On a PWM splitter 3 pin fans just run off 12v Molex power as they don't connect to the on-off signal of the PWM and always run 100%.

Anyway I'm developing a solution that may help you. A 4 pin PWM to 3 pin fan converter. It takes the motherboard PwM front your Asus board and spits out a DC voltage thatll power 3 pin fans. It works, so far, on 1-5 fans from full speed down to 400rpm or lower.

http://forums.overclockers.co.uk/showthread.php?t=18421145

You can either copy my design or give me a while and I can throw one or two together.

setter · 24 Jul 2012 at 16:38

Had a glance at that thread Tealc, a very interesting concept. Ill be purchasing a new fan controller soon, killed a few of the channels on my zalman zm mfc1 + a while back so it's up for replacement.

Tealc · 24 Jul 2012 at 17:22

Yeah it'll be particularly useful for people like me who just can't be bothered with adjusting fan speeds manually and don't actually like the auto settings on most fan controllers that don't actually respond to core temps. I have a bunch bunch of 3 pin fans and my motherboard just doesn't like them very much, so this'll fix it.

doyll · 24 Jul 2012 at 18:44

PWM splitter has a master cable for master rpm fan.. Only fan that sends rpm to motherboard. Other 4 fans get PWM signal same as master fan and of course all are powered by molex 12v. (you know all of this already)

Check that the rpm wire from master didn't break off of plug.. I've had that happen.

setter · 24 Jul 2012 at 18:48

Ill give that a check doyll, though the current 5 fan splitter is pre braided, so a cut in the wire would be hard to spot unless it was right at the connector. Tbh though, cooling is still good and noise isnt a problem either as all the fans are pretty quiet.

doyll · 24 Jul 2012 at 19:06

Pre-braided are junk. Their is no stress relief going into socket/plug but heatshrink making cable stiff right to the socket/plug.... Result is all movement of wire is in 2mm bit going into socket/plug.

That's where they break.

setter · 25 Jul 2012 at 18:15

Checked the cable and all connections are fine. But ive been lucky enough to find another two alpenfohn wingboost fans. Theese are identical PWM models to the one on the front of the cooler. So theyll be going onto the splitter and the redwings removed. This will allow me to run them in conjunction with the cpu fans. Amazing the things you can find in the bits and bobs drawers that you forgot you had.