A decent GPU would still be plenty profitable even after a 3x difficulty increase. For example the HD 7970 (about $400) currently mines $130/month, with electrical costs around $15/month assuming a worldwide average rate of $0.10/kWh, making a $115/month profit. After a 3x diff increase, this would turn to $45/mo revenues and $30/mo profits.

However this 140 Thash/s of Avalon chips is just a fraction of what is about to hit the network. All ASIC vendors combined, plus future Avalon deliveries will push the difficulty far more than 3x higher in the next 4-6 months.

Current ASICs do 150-200 Mhash/Joule (at 12V). Much better than GPUs topping out at 3-4 Mhash/Joule (at 12V).

Yeah. My estimate of the total amount invested in pre-ASIC hardware is 60 million, not counting power.

The key questions to predict ASIC mining profitability is:

- how much will be invested in ASIC hardware

- future prices of bitcoin

- how long will it take for the ASIC hardware to roll out

The only "easy-money" I see here is if you have access to ASIC mining hardware _right now_.

> Are they any more energy efficient than racks of GPUs?

Vastly. GPU's are space heaters compared to ASICs and FPGA's.