Why can't I play computer games in full screen?

I have a computer hooked up to my tv and i try to play games (halo) or just put a screen saver it say's itcant?

• i have a computer hooked up to my tv and i try to play games (halo) or just put a screen saver it say's it cant play becuase my video card is not installed but i installed it did everything that needed to be done to play a game but i still cant i know its the tv should i buy a hdmi converter to go from my computer to my tv?

• Answer:

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