get 8 if you are keeping the card for 2+ yearsgoing to pickup the 470, have decided whether to get the 4gb or 8gb model
searched for similar setups, and it's hard to say considering bios mods for 150% TDP over stock, all safety features disengaged hail mary runs to impress your buddies with for the 970/980Supposedly a fire strike score for the 480 http://www.3dmark.com/fs/8900159
Puts it at stock 980 performance.