Screen resolution is 1920x1080 already, but it still doesn't fit the screen

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http://askubuntu.com – I just did a fresh install. After installing the restricted video card driver, the screen shrunk even though the resolution is set to 1920x1080. There are black corners around the screen, so I'm pretty sure it's not utilizing all the space. What should I do to fix this? If it helps, my computer is a HP h8-1180d, using HDMI as the connection to the monitor (HowTos)