With current C31 code Vega 64 does 1.1 g/s at 180 W (settings: 1380 / 1000 @ 0.912V) making it the 2nd most profitable algorithm after CNR for V64 (!!!).
https://ibb.co/JmrWnF3Testing this :
6x Vega 64 rig
Clocks : ODT : 1344/1028/920mv
Results : 3.2 g/s for 6 cards => 0.53 g/s per card
Power(wall) : 1305 watts => approx 205 watts per card
No where near your 1.1 g/s @ 180 watts

Note: when i started the miner, it say
Name: Radeon RX Vega
Address: 9:0
Vendor: Advanced Micro Devices (AMD)
Memory: 8176 MByte (8171 MByte free)
Active: true (Selected Algorithm: Cuckatoo 31-4G)
May be need to enable 8gb solver for vega 64 ?