Is there any graphics/video cards coming out any time soon that would be good for mining? I'm thinking about building a rig with two AMD Radeon HD 5970's and I don't want to spend money on those cards if something better is coming out in the next 6 months - one year.
Thanks
-KCK402
5970 right now can be had for about $250-325 used and will do about 650-700 mhash when undervolted, and 3.2 mhash/j. Hard to find in good shape.
6990 is about the same as a 5970, but memory can be difficult to underclock, which means more electricity consumed. Has 4% less hashrate clock for clock than a 5970. I do not know how much power it uses. Price tag is probably about $300-400 used. More common than the 5970 but not by much.
7970 is a single GPU card. Retail about $420, or $400 if you're lucky. Possibly $375-350 used. I believe you can push 3.5 or higher mhash/joule.. Maybe 500 mhash when undervolted, or 700 with stock volts. Readily available.
7990 is not yet released. It will have 2 7970 GPU's on one card. Projected retail will likely be in the area of $800-$900. Assume a slightly higher mhash/joule and roughly double the mhash of a 7970. Probably due in 1-3 months.