I think on hashfast site they claimed they got 860ish GH per chip. I am not sure what gh/watt ratio it was, or if it was even stable.
http://hashfast.com/the-hashfast-golden-nonce/They tested up to around 1GHz (~750GH/s poolside most likely) with 1J/GH at the chip. You need to factor in VRM and PSU efficiency (as well as a bit for cooling) on top of that.