I have just bought a used Dell Ultrasharp 3007 30 inch monitor, I connected it to a G5 quadcore MAC computer with an NVIDIA 6600 video card, I have two DVI video ports, on one port the display can only be set on a maximum resolution of 1080X800, while when inserted on the other DVI port the display selector can show the various resolution options up to 2560 x 1600, but when any hiigher resolution than 1080X800 is selected the display turns pink with vertical stripes. I tried to connect it to my Mac Book Pro laptop which has a hi res of 1920X1200, but again if any higher res than 1080X800 is selected the same thing happens to the Dell display, turns pink and with stripes and nothing on the display is visible. What could the problem be? Thanks