its the fact CSGO is not a demanding game. depending whether or not you have vsync enabled...you may not be using more then 19% because, if vsyncd especially, your GPU isn't working hard enough to warrant more use. Try running fraps and checking your FPS. if you're locked at 30 or 60 FPS that would certainly explain things as i stated about not using more GPU cause it is not needed to achieve the frame rate set. however if your not vsync'd then you may have another issue going on. LMK what fraps says and where or not vsync is enabled