Intel motherboards have combined graphics, so you don’t need a dedicated card if you’re planning to use the computer for web browsing and emails. If you watch a lot of HD video or play a lot of games, you'll want a dedicated video card. If you are building a PC for gaming, then a GPU or external graphic card is extremely important and its selection prices can get pretty high and depend on your requirements. The GPU with more cores and cost is the better. A CD slot or tray is especially important for gamers who want physical games. While the Disc Tray can be cheaper, it is also easy to break down by itself or get jammed. The case is what holds your computers. The size of the case will be chosen by how many drives you install. Also the size of your motherboard. Cases range from cheap and functional to flashy and expensive. Select one that allows for optimal airflow, and install extra fans if necessary.I recommend a water cooling fan system. If you plan on using a lot of high-end components, you will be dealing with a lot more heat output than slower