Thread: Wiring Question (long)

OK, I'm finally ready to mount my PC in my car, and I'm trying to find a way to minimize the number of wires I'll need to run from the trunk to the dash. Here are all the required connections:
- serial cable from COM port on PC to LCD
- +12V and ground from PC to LCD (backlight)
- PS/2 for keypad
- 2 wires for ATX power switch
Here is what I want to do, and I nede input re. if this can be done without interferance becomming an issue:
1) Because the LCD only uses 3 pins from the serial port, I would also like to run the +12V and ground for the backlight through the serial cable
2) I would like to run the 6 wires for the PS/2 keypad plus the 2 wires for the ATX power switch through a CAT-5 cable

I'm not too worried about the part 2 because everything will be low voltage, but I'm not sure about running +12V through a serial cable. I know that the wires inside serial cables are a high guage (thin), so would I be better off running the +12V and the ground for the backlight seperately using thicker wires and should this be OK?
The reason I've chosen 1 serial cable and 1 CAT-5 cable is because I already have a 25ft. serial calbe and a 25ft. CAT-5 cable laying around, so I'd like to use these if possible.
Any advise would be greatly appreciated!

Thanks,
Mike.