Group DMT has 7 modes:
           mode 4: 640x480 @ 60Hz 4:3, clock:25MHz progressive 
           mode 9: 800x600 @ 60Hz 4:3, clock:40MHz progressive 
           mode 16: 1024x768 @ 60Hz 4:3, clock:65MHz progressive 
           mode 21: 1152x864 @ 75Hz 4:3, clock:108MHz progressive 
           mode 35: 1280x1024 @ 60Hz 5:4, clock:108MHz progressive 
           mode 58: 1680x1050 @ 60Hz 16:10, clock:146MHz progressive 
           mode 83: 1600x900 @ 60Hz 16:9, clock:108MHz progressive 
