I have a homework question regarding computer hardware. Simply, which parts of the PC would need to be upgraded or added in order to improve the gaming performance for a PC?
As of right now, the only things I can think is the CPU Processor, RAM & Graphics Card.

Is there anything else that I am missing?

Don’t forget the HDD, though it ain’t matter that much. Better concentrate on the CPU, VGA and RAM. Oh a good high-end motherboard too.