RPM on fan

[Miknow]

I only have 2 fan headers on my mobo and Im gonna use 4 fans. Problem is I wanted to know if the mobo detects fan speed on the 4-pin connecters I know it does on the 3-pin but Im planning on using Swiftechs M371 and they have peltiers on them people perferred I use the 4-pin for enough power but then would I still get reading of the fan speed

 

[Storm]

If the fan has a positive and a negative cable and nothing else into the 4 pin plug, then you can't monitor the fan speed. However, if it has a spare cable (yellow probably) then this is likely to be the RPM sensor, and it's possible to attach this to a 3 pin plug and then plug it in to get an RPM reading, without worrying that you're overpowering your mobo fan headers.

 

[markedmundb]

Best thing to do is if it's got a yellow (or Blue?/Green?) cable at one end (opposite the black lead), pull it from it the plug and attach it to the mobo header.