Anyway to convert 4pin fans to 3 pin?

[russr]

Antec SX830 case comes with two rear 4 pin 80mm fans. IS there anyway I can plug at least one of them into the 3pin connector on mobo to have speed sensing?

 

[bacillus]

in order for fan speed sensing, the fan itself must have a 3rd wire (tachometer lead) which is most unlikely!