Sorry, I havent been able to figure out what motherboard cables your talking about? The PSU is connected to the PC via USB and spliced AC cable only. Are you talking about the polarity of the spliced AC cable?
But nope, definitely don't have that cable. My power button connects directly to the motherboard.
But ya, it is working the way I want it now, EXCPET it is still randomly going into hibernate for no apparent reason (not hard shutdown as I originally thought). It will happen right when I turn my car on, or half way through my trip. Completely random. Other than that it seems to be operating fine..
Here's a picture of what my HP looks like: