PWM connector WTF

[mtah]

I got myself a Nanoxia PWMX fan adapter which transforms PWM signals to plain DC control (since none of the ASUS P8P67 boards seem to support DC control of the CPU fan). I also got myself three of these extension cables to reach in my case: http://www.akasa.com.tw/update.php?...ype_sub=Fan Cable Adapters&model=AK-CBFA01-30

But look at the connector pegs:

Extension cable:

Nanoxia:

The pegs are further apart on the Nanoxia connector, which means I'll have to break it to make it fit!. The extension cable uses the kind of connectors I see in the PWM specification, but what's up with the other connector?

 

[Tsumi]

PWM can be manually controlled by varying DC voltage (which is how 3-pin non-PWM fans work). Not sure what lead you to believe that can't be done. I think all boards, especially high-end ones, can control fans by varying voltage. Are you sure you're setting things up correctly?

 

[mtah]

PWM can be manually controlled by varying DC voltage (which is how 3-pin non-PWM fans work). Not sure what lead you to believe that can't be done. I think all boards, especially high-end ones, can control fans by varying voltage. Are you sure you're setting things up correctly?

I have two non-PWM fans (the stock Noctua NH-D14 fans) which I want my ASUS board to control. When I bought board and HSF, I assumed that the board would be able to voltage control the fan when connected to the CPU_FAN header. However, ASUS used a fan controller chip (Nuvoton NCT6776F) that seems to only support PWM control, which means my fans are constantly running at max speed (see this thread). I hope that explains my situation .

 

[mtah]

Hooked it up, works well (although I had to physically alter the connectors). Fan speed is now controlled by the motherboard. What a stupid regression by ASUS though.

 

[plugwash]

The extension cable uses the kind of connectors I see in the PWM specification, but what's up with the other connector?

PWM fans use a special variant of the molex KK that has four pins but has the keying system of a three pin KK connector.

It seems nanoxia either cheaped out or were incompetant and used a normal 4 pin KK (or KK clone) shell rather than the special variant. This will mate with a standard motherboard fan header (either a PWM one or a non-PWM one) but won't be keyed properly (specifically it will be able to be plugged in in two positions only one of which is correct).

Seperately it seems that the connectors used on fan extension cables have an extra plastic shroud on them that is not on the standard motherboard connectors.

Combine the extra shroud on the extension cable with nanoxia's use of the wrong connector and you get the problem you ran into.