I was able to plug tach wire to both MOBO and TT controller. Works as a charm!
Spent 6 hours rewiring all my 5 fans. Got rid of one of two controlles by plugging two fans in one socket.
When there are two fans, tach from the first goes to MOBO, tach from the second goes to TT controller. When there is one fan (my rear fan), tach goes both to MOBO and TT controller.
I made some photos