its iffy, you have to get the vertion with the full 10 memory chips for possibility of max memory which i think you usually get with asus
http://forums.anandtech.com/showthread.php?t=2084787
basically you reflash the bios and hope it works.. it might be sucessful it might fail and you can usually restore to 465 again.
even when you do unlock it the sofware you will sometimes get close to 470 performance in the best cases but still not on par with a real 470... but it gives it a pretty signifigant boost... when it works
note this will not necessarily work, at worst it will likely void your warrenty but there is a possibility of a 470 but due to defects it may require it to stay at stock frequesncies.