None! This is a fully beginner tutorial. Remember though, this is an investment – know exactly what your needs are. Wanting to be a developer vs. wanting to play Counter Strike on medium settings vs. wanting to play [insert crazy intensive beautiful game] on ultra settings and recording it is all going to require different budgets.
Know your environment too. Is this a PC that’s going to be in your room forever? Is this a machine you want to transport to and from work/college/hackathons?
