1. disable/enable vega in device manager.
2. Check HBM segment is off. When miner starts vega's name must be gfx900(not gfx901).
3. double check miner settings.
3. set target temp to 55.
Card recognized as gfx900 has lots of more trouble mining.
I do have 6 identical Sapphire 64 and one was identified as gfx900 by xmr-stak. SRBMiner identified all as gfx901.
Only few cards are identified as 900 and no one really knows why cuz ive already asked around in several places.
To the guy above, yes, you need to add 30 to 40W to any software measurement. This is old news.