So my current pc is semi-decent, I have had it for about a year-ish and when I first got it I was amazed as it was my first good computer I could get 300-370 fps on gmod and csgo but now I even got as low as 20fps recently. So I have decided I am going to assemble a new one, however I don't know much about what parts are needed to have other parts, I want to have a nvidia gtx 980ti graphics card, but I don't know what other things I will need to buy to accompany it, if anyone can help me I would greatly appreciate it. Thanks in advance