I'm looking to do a gaming PC build with my son for his 16th birthday . I do not know the games he wants to play I have a budget $500 not including monitor or keyboards and mouse or pcu. I accidentally bought a evga 550 b5 pcu .I'm trying to find compatible parts in my budget with out asking my son question that would give it away. I'm out of touch since windows xp and 1's & 0's hopefully someone can help me out .