Its just some old nvidia 128 mb card that I'm using to do web browsing and stuff until my R9 270 comes in, since I don't have integrated graphics on my mobo.
The problem is since the TV doesn't fully support the resolution, instead of allowing for black edges or parts that are cut off at the edges it just doesn't show anything at all.
It basically acts like it would when it would say "No signal" but it says not supported instead.
EDIT: tried what you said, psychomutt, it didn't work.