[ubuntu] determining max resolution of TV?

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http://ubuntuforums.org – for whatever reason my TV via VGA tells my g7-1070us laptop that its max resolution is 1024x768. I somehow doubt this from the level of blurriness when I set it to this max resolution. I'd like to override this via xrandr but I don't know what the actual max resolution of the TV is. I've tried some random resolutions like 1366x760 but I often get a black screen when I try. The TV is a lg 42pc3dv. Is there any systematic way of approaching this issue? (Hardware)