Hi, I just became the proud new owner of a 27" ACD after first updating my 3.1 Mac Pro with a HD5770. Card works perfect on my old 19" monitor but when I hooked up the 27" ACD, the video becomes sluggish and there's definitely lag present between video and audio. Also going into Expose is pretty sluggish. My MP: 2x2.8Ghz, 4Gb RAM, HD5770 1Gb. Any ideas anyone? Maybe something went wrong with a driver install? See attachment.