What kind of TH2G ? Digital or Analog Edition ?
What kind of GPU ?
I do have 2 TH2G analog edition and I was able to go only at 6x800x600@60hz
using a mac pro 2,66 and ATI xt1900 .
Also what kind of HD ? if you run 6x1024x768 you need a good ( very good ) harddrive .