Only do it for the fun of it, or as others suggested, mine litecoin. I'm currently running a 7770 at about 220 MH/s 24/7, which is only getting me around 0.02 BTC a day. That's less than electricity costs. The card will _never_ pay itself off. But i still think it's fun playing around with, so I do it anyways Had the option of buying five 5970's at about a third of retail price today, great offer, but wouldn't even make sense, since they would never be able to make more than they use in electricity (unless exchange rate skyrockets).