You need to increase core clocks and find your best hashrate/watt ratio.
I've got the pool working good now, but trying to solo is still giving my HW errors. I'm using the default .bat file, just changing the pool and port to local wallet. And of course my user name and password. Windows 10, 18.6 drivers, vega 64s.
Can you post your command line arguments how you are trying to run it? Also is it on linux or windows and the drivers version.
I'm getting HW errors on both solo and pool. They go away if I drop the intensity way down, but then I'm only getting about 3MHs per vega. My 1070's are running 450MH with ccminer.