|Well, you only needed to try one other monitor but you did prove it is the motherboard.|
Why don't you believe it could be the motherboard? If your AC is bad on your car it doesn't affect the radio. See, they are different parts of a system. While the system is degraded a unit is bad.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.