I agree with Nim he's just stating facts on these cards, they are power pigs! Yes if you have 850-1000w power supply these cards rock and yes can max out any game but compared to 2-gtx 580s or 2- 680s they can hold their own but are hampered by older hardware which is what makes the newer cards superior, I had 1 gtx 480 and it was a great card but I sold it for a Ati 5870 which matches the same performance at a lower power rate in crossfire to 2- 480gtx in sli the 480s are better by 10% compared to the 5870s but, the newest offerings (680 and 7970) offer better performance with out overclocking and high temps. These are great cards. If I were to buy cards I would ask the same questions overclock?, warranty?, brand?, registered?. Based on facts I would keep them if you aren't having issues with them and maybe sell them once the next gen comes out, I personally only do single cards less complicated, less money, and cards out right now offer same performance or better than previous gen 2 card setups. IE; GTX Titan offers same performance than 2-580s in sli and comes with in 10% of 2-gtx 680's.
On a side note, There is no need to turn this into an argument we are just stating facts and trying to help.