my frd just gave me 2 evga 8800gt 512mb. i want to run it in sli, but my frd said my psu (Zumax 550W Power Supply) is not enought for 2 cards. right now, i am running on one card. However, when i try to change the resolution back to 1280x1024, my screen only shows 3/2 or 3/5 on the screen. i could use my mouse to move the screen up and down, even left and right. Can anyone explain why? my monitor is dell 19" lcd that i bought almost 4 yrs ago.