yes , its full hd , tv's dont have a higher resolution ... its showing no support mode because ur trying something other than 1920x1080 , which is full hd . ull also need a good wire for vga because interference problems will cause unclear picture .
do you have intel or nvidia graphics ? for nvidia go to nvidia control panel , set up multiple displays , detect display , and in dual view mode , change the resolution to 1920x1080 .