RV770 version A11, which is usually a pre-production version, needed 1.26V to work, and it looks like the ATI boys did improve the A12 chip.

The A12 revision, which is the one that ATI usually ships to market, only needs 1.13V, which means it's significantly cooler and can be clocked higher. Both voltages are referring to the samples clocked to 625MHz, but we have a strong feeling that the final units will work at higher than 625MHz.

The clock details are something that the company finalizes shortly before the launch. so this is really out in the open.