Post originale di: Steve Godun ,
Since you get good video on an external screen it's not a bad motherboard. Either your screen's display drivers are having issues, the display connector on the motherboard is damaged, or the display cable is damaged. Likely not the screen display drivers; they usually go bad only when the computer has been dropped, banged around, or had a weight set on the (closed) screen. So I'll go with either a bad display cable or display connector. Pull out your magnifying glass and examine the display connector on the motherboard for damage or dirt/moisture residue/corrosion. Clean it with some >91% isopropyl and let it dry. Check the display connector as well for similar signs of damage; GENTLY tug the wires to make sure they're all still attached to the harness. PS: For future reference, NEVER use compressed air to blow moisture "out" of electronics. While you may get some or even most of it, you'll never get all of it, and there's an almost certain opportunity for some of that moisture to get blown into areas where it can create a short circuit.