Every now and again a certain GPU will be unlockable to a more powerful version, some 6950's can unlock to a 6970 i believe, and the oldschool 9500 pro would frequently unlock to a 9700 pro, and as for it being legal of course it is, you own the hardware after purchase. and as long as its only a softmod aka firmware update then your warranty is still good, however if you have to hardmod it then you void the waranty.