I've done it, it works just fine so long as nobody attempts to use a standard 4 pin Mole to power the sequence from their PSU. That would so not be good.
I plugged one fan into the MoBo header. Then I plugged another Mole into it's 4pin Mole and VIOLA we have power for both provided by the MoBo. Just remember to keep the fans to 3 or less. MoBo's eventually fail at that point if you start stacking more than it can handle. Since I don't know every MoBo, I choose to recommend no more than 3 fans in a daisy. I've seen as many as 6 as the recommended limit however.
Originally Posted by WTHbot
I've never done it but if I remember correctly you can mount 4pin connectors on 3pin headers.