My GPUs, on Windows 7 and 8, 64 bit.
Gigabyte Windforce triple fan 280X's, engine 1100 memory 1500 powertune +20, intensity 19 = 2.30 Mhash
Sapphire and HIS 7950s, same settings except 1050 engine, 1450 memory, 2.0 Mhash
A variety of 270X's, 1100/1450 speeds, otherwise same settings, 1.35 to...