Black screen only, after installing , single MSI GTX980 Gaming card to replace GTX680 cards in SLI. When GTX680 is put back, screen is working ok. The GTX680 driver was removed and new driver for GTX980 was installed prior to installing GTX980 card. Computer build are: motherboard--asus Rampage 4 Extreme. Power supply--Enermax Galaxy 1000w Memory--corsair 16g CPU--I7 3820 Am I having a compatibility issue !! ??