2060 Mhash/sec @ 498 watts -- 4.13Mhash/watt (918 mV, 900Mhz/160Mhz) (all cards stable)
If you still think these cards aren't efficient, you're drunk.
Fascinating! That's with 4x 7970?
3x 7970
Mining: 925/150mhz, 865mv, 354 watts + 270 idle = 624W.
~1650mh/s
Even with similar clocking, you are pulling 50% better efficiency than the OP! You added an entire extra card, and dropped more than 100 watts. How???