Which version of graphics card do you have? This can be answered by running the command
One of the lines in the output should look similar to this "01:05.0 VGA compatible controller: ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics]"
In this case, we would have the Radeon HD 3200 card.
But, that's not all.
Do you have 32-bit Linux or 64-bit Linux?
If you don't know, you're probably using the 32-bit Linux version.
Download link: support.amd.com/us/gpudownload/Pages/index.aspx