As for as gaming performance, my current 3570K@4.0Ghz clearly holds the Vega back but it still manages to deliver ~120-150FPS on newer franchises at my monitor's native resolution (2560x1440) with all of the works. Freesync eliminates screen tearing and makes motion blur look more "natural".
I'm aware that 1080Ti is faster with lower power consumption but you need to get a Gsync monitor and Nvidia has no incentive to support Freesync in light of Vega's lackluster launch. It feels like Vega 64 is Hawaii 2.0. There's potential in the hardware, but the real issue is coding the software to properly harness it. Nvidia has a massive jump start here. I wouldn't be too shock that Vega 64 manages to distances itself from the 1080 in next year or so, but it will never catch up to 1080Ti in terms of gaming performance.
After waiting patiently for the last several months, I bit the bullet and bought a Vega 64 LC edition. I was so close to capitulating and getting a 1080Ti (great card), but the recent advances in AMD driver support for Win/Linux has won me over.
As well, I've hedged that the gaming/compute performance will improve as AMD enhances drivers/support over time.
I've been running an R9 390 for the last several years on an ASUS MG279Q FreeSync (1440p) monitor and it has been good for me, although gaming at 1440p on the newer AAA titles has been a let down.
I've been able to successfully dial back the voltage on my current R9 390, staying above the point of instability, while significantly reducing the power/hear/noise. I suspect that with Vega, I should be able to do the same (unless I receive a 'lemon' card).
Any good pointers on tweaking the voltage(s) on Vega ? (I currently use MSI afterburner for the R9 390)
Prior to the R9 390 and MG279Q combo, I was firmly in the green team camp, until the nonsense of the green team unable/unwilling to support the VESA 1.2A open standard (yes, I know that supporting the VRR from 1.2A is optional)
BTW, I used to run my 3570K at the stock frequency - however I recently delidded it. Many have been able to run at 5GHz, but I run mine 'conservatively' at 4.7GHz with no issue on an ASUS Z77 motherboard.