MacBookPro (13” 2017 Touch Bar) + Sonnet 650W + GIGABYTE VEGA RX 64 OC GAMING 8G
Definitely I returned the gigabyte rx 64 Gaming OC 8GB. Too many problems with my Mac and in many forums is explained that this GPU (Vega 65 and 56) comes factory defective most of the times. The store gave me the reason about the defects of the GPU and I have requested a replacement for the Sapphire Nitro + Radeon RX Vega64 8GB HBM2 which runs perfectly with the sonnet 650w as is said in this post. For future readers of ths thread, I definitely do not recommend the Gigabyte RX Vega 64 Gaming OC 8GB: too risky.
It works perfect in my Mantiz Venus and without any single problem, not risky at all. It is just noisy, but as most of the VEGAs...
But obviously yours, could be defective, but don't say risky, as you are not right to say it. Make sure your TB3 case is fine... otherwise you will repeat the situation with another card...
Changed to a Sapphire Nitro+ Vega 64 (because the gigabyte was REALLY noisy), which still noisy but better... Pretty good so far.
And fits in the Mantiz with no modding!!