Guess Frontier Edition with 16gb can do 2.5 khashes. But one will need 32gb of system RAM ))

2 Hellae

Miner settings are standart - 2 threads with 2016 and 1800 intensity.
HBCC set to 14400 mb, gpu-z can sometimes drop speed so need do reapply HBCC settings to fix it. Or not to use gpu-z ))
Power tuning is private yet, sorry.