If your vega wull be with Hynix mem then expect no more than 1.8kh/s cryptonight, neo and eth speeds - don't know
I think you just got unlucky with the Hynix. My gigabyte custom V56 with Hynix does 1950+ no softpowerplay mod, just 1411mhz clock 940mem 0 power target. Probably chews through many watts of power, but at least it's stable!