What are you going to be using the computer for? And are you upgrading on the same motherboard now, or doing a new process and need a new motherboard as well?
Dude, you're confusing. You mean it needs to support 8GB of 1600 Ram? Or include it? How about you tell us your total budget and what all you'd like to replace.
Is this $500 for a completely new system? And do you have any parts in your old system that could be brought over? You have to be much more clear about what you're looking for before anyone can help you with this.