The 465 is a castrated version of a 470 that nvidia made only due to poor yields. They card had defective sectors so nvidia disabled them and sold the card as a 465. It has a thermals of a 470 yet the speed of a 460.

The 460 on the other hand is a whole different die than a 465 and was made from the ground up. Its thermals are about 33% less than a 465 and performs about the same as a 460 at stock speeds. When overclocked about 25% (which is not guaranteed) an oc 460 is about the same speed as a 470.

-------------------------------------------------

Nvidia named the card 465 for the 465 was a stopgap until the 460s came out, and they figured it would be easier to clearance them when the 460s came out if the 465 had a higher number.

-------------------------------------------------

Now there were some reports of fully function 470s sold as 465s due to demand at that price point before the 460 came out. The card was physically a 470 but the bios was that of a 465 thus the card performed as a 465 unless you flashed the bios with a 470 bios. That said this physically won't work unless your card had the right number of memory chips. And the chances of that happen now a days are about nil since this was months ago, the 460s are now out, and vendors don't want to sell a more expensive card at a cheaper price just because.