Multi Core

On gmod on the video options it says Multi Core Rendering, when I select the drop down list there is no options? I have an AMD Phenom 9650 Quad Core 2.3 Ghz so I have 4 cores why can’t I multicore render?

Multicore rendering is not supported on Garry’s Mod.

Then why is there an option for it?

There is not. Simply a label with a drop down box containing no values.

Is there anyway to make it multicore?