The bitcoin network difficulty is rising so fast that even the first-gen ASICs are becoming obsolete.
For example if you have a good Radeon HD7970, you can get about .8 GH/s. Based on the rate of difficulty increase the 7970 would mine about 0.02 BTC in all of November 2013 and 0.01 BTC in December 2013 and < 0.01/month after that.
For various reasons Nvidia cards are slower at BTC mining than AMD. The fastest Nvidia card, the Tesla S2070, can only hash about 0.750 GH/s.
Even 60GH/s ASIC miners will be earning < 0.10 BTC per month by March 2014. In August 2013 a 60GH/s miner would make ~0.8 BTC PER DAY. That's how quickly the difficulty is increasing.
At this point no GPU would make a decent bitcoin miner, except as a hobby.
For example if you have a good Radeon HD7970, you can get about .8 GH/s. Based on the rate of difficulty increase the 7970 would mine about 0.02 BTC in all of November 2013 and 0.01 BTC in December 2013 and < 0.01/month after that.
For various reasons Nvidia cards are slower at BTC mining than AMD. The fastest Nvidia card, the Tesla S2070, can only hash about 0.750 GH/s.
Even 60GH/s ASIC miners will be earning < 0.10 BTC per month by March 2014. In August 2013 a 60GH/s miner would make ~0.8 BTC PER DAY. That's how quickly the difficulty is increasing.
At this point no GPU would make a decent bitcoin miner, except as a hobby.