connecting pc to tv probs

[MaD_FOr_iT]

Hi i got a nvidia gtx 480 and i connecting to my lg plasma tv with a dvi to hdmi lead and i get like little dots it kinda looks like interference unless i set the refresh rate to 30 htz from 60 htz, i use to have a gtx 8800gtx and that was oki @ 60 htz but since i got my new card i get the dots my tv can take 100htz so dont think thats the prob maybee i need a beter quality lead? any ideas i would be greatfull thxx