this maye be old news but i couldent fins anything,also not sure how legit these specs n pics are but.
i think you can tell from the cooler its gna be cooler than the 480
http://www.nordichardware.com/news/71-graphics/41570-the-geforce-gtx-580-mystery-is-clearing.html
i think you can tell from the cooler its gna be cooler than the 480
http://www.nordichardware.com/news/71-graphics/41570-the-geforce-gtx-580-mystery-is-clearing.html