Hi, I will soon be upgrading my HP pavilion p6631p to a gaming rig. I will be upgrading to graphics card to a AMD ATI Radeon HD 7870, adding two more sticks of memory, and putting in a new PSU (Rosewill Hive Series 650W). First, I want to know if the graphic card will and if yes, how comfortably will it fit? Secondly, if you know if I will get good airflow out of it? Lastly, how much space must a you have in your computer to maintain good airflow?