For some reason Windows 8 recognizes only default speed of the processor and not actual speed it's running at the time, weather it's overclocked or running at turbo speed. I have an AMD Phenom II x4 965 BE that runs at 4.2 GHz all the time but W8 recognizes it as running at 3.4 GHZ as this is it's default speed.
You can use a program like this "http://download.cnet.com/CPU-Z/3000-2086_4-10050423.html"
to detect the true speed it is running at the time.
You can check at this site if and at which settings it can be run and also which kinds of frame rates you can expect.
Call of Duty: Ghosts System Requirements and Call of Duty: Ghosts requirements for PC Games