600 khs ?? 
sry.. but it looks for me like a rly bad joke 
with NSGminer 0.9.4 my esault for each vega64 is ~80-100khs depends on powerlimit. im running my rigs on Claymore's NeoScrypt AMD GPU Miner v1.2 with powlim -25, and each vega64 is running on 1.7Mhs. together 1 rig with 6 cards ~10.2 Mhs
sry.. but it looks for me like a rly bad joke with NSGminer 0.9.4 my esault for each vega64 is ~80-100khs depends on powerlimit. im running my rigs on Claymore's NeoScrypt AMD GPU Miner v1.2 with powlim -25, and each vega64 is running on 1.7Mhs. together 1 rig with 6 cards ~10.2 Mhs