You want to measure the revolutions of your fans - right ? Fans with a standard powersupply connector (explanation here) don't have that possibility - even some fans with molex connectors don't.

This is a fan with a molex connector - the yellow wire is used to measure the fan revolutions.

This is a fan without the possibility to measure the revolutions - but as you see there are a unused soldering point there - guess what that point is for .......... If you wish to use the standard powersupply to the fan you could still use a wire to a vacant molex header on your motherboard - take care to connect it to the correct pin on the motherboard header.

We have checked 12 brands of different sizes and they all had that solderpoint !