When I first boot up my computer, everything will run perfectly. But I will begin to play a game and often it will freeze or lag and the only way I can exit the game is by going into my task manager and ending the task. Once I do that, (if I can), my computer will then the lag with almost every move of the mouse. I first thought it was bad RAM, but I replaced it and it's giving me the same issues. I think it may be my graphics card, which I purchased from a friend of mine. My next guess is my motherboard, which I got on clearance from a store. This is my first build and everything is a fresh install, which rules out a virus.