As best I can tell it does not seem to be clock-blocked for me. My stock default voltage is 1.070V and I was able to use the EVC2 to set a +50mV offset to get it to about 1.125V and the core offset of +190 seems to hold. This was bumping up to just under 800W with a moderate load Vulkan stress test.
The first image is with the EVC2 connected, so HWiNFO64 cannot "see" the WireView. The second image is with the EVC2 USB cable unplugged after applying the voltage offset so that the WireView sensor show data in the OSD. GPU-Z doesn't show much of anything accurately in terms of voltage, power or PerfCap reasons at this point. The second image shows WireView Pro II sensors in RTSS overlay.
Edit 1: the way the new Imgur UI is made totally sucks. Changing to the old style only fixes the look and feel, but not the degraded functionality. Very lame, and the way it is nearly impossible to post direct image links that skip their ugly sucky crap landing page really is super annoying. Seems like every time you find something awesome, some idiot (or group of idiots) find a way to screw it up. I may have to start looking for an alternative that isn't a piece of trash, but I am not sure there is one.
Edit 2: I'm trying Image Chest now. Hopefully it will be what Imgur used to be. Updated images and links.