Hi,
The red and white wires from the USB port are the power supply.
The red is +ve and white is Earth (or Ground) so they should go to the red and black on the motherboard.
The wiring for the motherboard seems to follow the convention for USB connections i.e. red =+ve batt, black = earth, white and green are the data wires (+ve and -ve).
If the USB port had 4 wires the same colour as the motherboard then it would be wire for wire.
Here’s an image showing the USB wiring colours
[image|2473243]
(click on image to enlarge)
Hopefully you may be able to joint and sleeve some new wires to the existing ones.