Hey thanks for the reply. I too managed to solve my issue as well. I had the motherboard in a wooden case that I had built. So after much troubleshooting, i cut a piece of metal out of a computer case that was motherboard-sized and put in in the box like so:
Motherboard-->Metal Standoffs-->Metal Case Piece-->Wood Box
I then made a ground with an 8 gauge wire hooked up to an "O" ring connector and put that O ring inbetween the screw in the motherboard and the standoff of the metal piece of the case, therefore grounding the entire motherboard to the car. Guess what? worked like a charm! I now have nearly no noise at all, and the lines on my monitor have vanished! I have yet to take it out driving and see if the engine whine is gone however...lol
The logic was that a normal computer is connected to the case via metal standoffs. The entire case is then grounded to the wall because there is a ground pin on power cords, and that ground makes its way through the motherboards ground points. ok, that probably doesnt make sense in words, but it solved my problem
And btw, i have a pioneer 300 watt 4 channel amp, so I think im good
Thanks for the reply to an older thread though!