Associate
When I bought my Vega 64 AC as soon as I went into a game I got the black screens and eventually it rebooted. Turned out my 700w PSU just couldn't handle it and AMD are right in saying minimum spec is 750w. Fitted a new FSP Hydro-G 850w and since then it's been gaming bliss. I notice a few of you that are having the black screens have the AIO version and AMD recommend a 1000w PSU to run them.
Anything less and you're close to the edge TBH and reading some of the posts people are getting them to run in power save mode or bios 2 but they won't run at balanced/stock. Whichever way you look at it Vega is a power hog and you really do need the recommended spec to make it run right. If you haven't got that PSU either you need to buy a new one or don't buy a Vega card if you don't want to be disappointed. Sad but that seems to be where we are with Vega. Great card if you can tame the power!
Now that I finally have my Vega64 AC installed, I've had no problems running it overclocked on a 600W PSU (Be Quiet! Pure Power 10).
At stock settings (balanced power profile etc) I saw a peak system power draw (measured at the wall) of 390W (though typical draw was nearer 300W) during Timespy demo (graphics benchmark score of 6948 with 17.8.2 drivers).
The highest peak system power draw I saw was 544W (typical draw in the 400-480W range) overclocked to 1707MHz at stock voltage (HBM at 1070MHz) and +50% power limit. At these settings I got a graphics benchmark score of 7628, but was still able to get 7602 at 1692MHz with an undervolt to 1150 and a corresponding peak draw of 492W.