Vega is ... hot. In stock it takes about 400-450W in dual, 300-350W in ETH-only mode at about 33MH/s. And it's throttling like hell. It's very good in dual mining mode, but it's too hot.
This confirms what MSI executive said that "Vega takes lot of power". Hopefully AIB partners will come up with better cooling solutions. Did you get your hands on a sample vega to test ? Not the FE of course.