Recently my brother lend me this Workstation. Unfortunately, it is a workstation and can only play Middle Earth: Shadow of Mordor on lowest setting, and it only get 27 FPS max. Right now, it has Nvidia Quadro 600 as its GPU and I want to upgrade it for gaming performance, at least to be able to play Shadow of Mordor in high setting with 60 fps. I'm willing to spend about $300 on it, so what best GPU to get to satisfy my needs for gaming? Thankyou