i try stock and 64 bios and this setup
GPU 1408/940mv
MEM 990/940mv
Work 6-8 hour and BLOCK
6vega give 11200HR and use 1020W form Wall
i try
GPU 1460/ 960mv
MEM 950 / 960mv
work 10 hour and block
6vega give 11700HR and use 1080W form Wall
any try move switsh- silent-standard-OC ?
i use this sotf powertable
-snip-
11.2 kh/s is not bad for Sapphire Vega 56 GPUs with Hynix memory. That is already 1860+ (11200/6) for each Vega 56. Your power consumption at 1 kw is also not bad. I would not go and try overclocking more than that because as you see, it is not only less efficient (unless you have really cheap electricity) but could also be unstable.
If your rig runs smooth without crashing then keep it that way. Good job!