Use pins on ports 0 to 3. Upper ports have no hardware connection on PSoC 4, so tachometer won't work
I guess you are using PSoC 4L. The fan tach signals uses the DSI, which is not avaliable in Ports 7, 8 and 9. Any other ports are good to use it.
I'm sorry, from the title of your post, you are using PSoC 4M. Only Ports 0, 1, 2 and 3 have DSI connections.