Just purchased a small usb hub (x4) that is powered up by external source (not just the usb from the mobo), since i have more than 10 usb devices attached altogether and sometimes there was not enough current from the mobo to the old hub (with no external power source) that i used to have.
Now what i noticed when i plugged the usb cable of the hub to the mobo with the PCbeing closed, was that suddenly the three 8' fans that i have in the case plus the lead from the 12' fan of the cpu started working! With the PC closed. When i disconnect the hub from the computer this stops. It also stops when i disconnect the hub from its power source leaving only the usb attached to the mobo.
Somehow it seems like current is being transferred to the mobo while the PC is closed by the hub - and i don't know why or whether it is safe. Is it?