If your box gives error
 

Connect your box to rear usb port instead of front usb port becaue rear usb port yeild more power(current not voltage) that front usb


And smaller usb extenion cable to connect your box




Reason :
==>Yes there is a difference, the front port has 1000mA of allocated current, while the rear have only 500mA of current, per port, 1000mA total for the rear ports.


==>True, there is certainly a tiny bit of voltage drop over a longer distance, but that's not going to affect the overall output much.


==>Also depend on device you connect and may vary to motherboard also


==>to try
try flashing two phones same times with box connected to front usb
at your own risk