I have the same kinda setup, the Sager laptops are annoying in the fact that you can't completely bypass the intel chipset. You have to rightclick and if you have the Switchable graphics box, open that up and make sure the client is running on the appropriate setting for max/plugged in.

Regardless what the drop down box said in game, which always seems to say Intel HD4000, it should be running using the Radeon card since I have the same laptop as you and am running on Maximum.