I just installed Ubuntu 18 on my gaming rig with the 18.20 beta driver and Vulkan. It works fine, I just played a bit of ROTR and Firewatch and am glad that the Linux drivers work fine.
One thing I noticed was an increase in system power draw, compared to Windows. What used to be 50-55 Watts at the wall is now 65-70 Watts even in a pretty vanilla Ubuntu. I thought at first that the CPU frequencies were too high, but then found that it clocks dynamically just as it should.
Now, the power draw figures remind me a lot of those in Windows when I had run the HBM 2 on my Vega at the highest state because I had forgotten to set Status 0 as minimum after fiddling around a bit and tweaking my card. I suspect that HBM running at full tilt in desptop idle scenarios is causing the increased power draw, but I don't know how to check this as the Linux drivers don't come with something like the mighty Wattman tool.
Is there a way to check if the GPU is the culprit here?