why the 7970 over 680?
It's better value for your money, and will perform slightly better.
okay. thanks for all the help.
If you want to make it future proof you will want to go to with LGA-2011 because with Intel's new processors (code name hasewell) with LGA-1150 socket are coming out during the summer which is makeing LGA-1155 a dead-end socket. While with ivy-bridge-E waiting to be announced, LGA-2011 is a safer bet.