Where to plug a extra fan in to the TX1?

We’re installing our TX1 into a case. For optimal operation we want to keep the temperatures low. We have a fan that works from 5v to 3.8v and we can install in the case.

Can anyone tell me which pins to connect it to, or do we need some external power for it?

Thanks

You can find in schematic, there are many pins for it, such as pin 2/4 of J21, VDD_5V0_IO_SYS, same rail as original fan on TX1. Pay attention the power consumption of your fan should not be too much.