Have you checked your power settings in Windows? Check that in Advanced Power Settings that Processor Power Management > Maximum Processor State is at 100%.
This article makes me feel better about my impulse upgrade from my Fury Nano to a Vega 64 LE (at MSRP, thankfully). I think next card, i'd like something not weirdly power limited for a change.
The normal power limits for 2700X is 141W PPT (Package power limit), 95A TDC (Mobo current limit), and 140A EDC (Some other, more critical, current limit??? Haven't figured it out).
Turning on Precision Boost Overdrive cranks those to "the max": PPT gets uncapped to 1000W, TDC to 114A, and EDC...