Here is my first test.

Driver: 18.6.1 with Dragonmike PPT (txs Mike :-))
Rig: 2x Vega56 reference (V64 bios) + 1x Vega 64 Strix + 1x RX570
Miner: TeamRedMiner 0.4.3
Core: 1280/870mV Mem: 1100/870mV (in OverdriveNtool)

Todxx settings for Vegas, with "i" selected only Vegas: --i 0,2,3 --CL 20 --RAS 33 --RCDRD 12 --RCDWR 5 --RC 44 --RP 10 --RRDS 3 --RRDL 3 --RTP 5 --FAW 16 --CWL 7 --WTRS 4 --WTRL 9 --WR 16 --WRRD 1 --RDWR 19 --REF 3900 --MRD 8 --MOD 15 --PD 8 --CKSRE 10 --CKSRX 10 --RFC 300

Same settings of the miner and Turtle/Loki mining:
 
Vega 56 (64 bios) from 19.2 to 20.3 hk/s ;-) L20+20
Vega 64 Asus Strix from 19.5 to 13.2 hk/s ;-( L24+24

So, for reference card work nice, but need to tune for every card...

Tested Vega 64 Strix config in miner from L18+18 to L28+28 including 20+20 etc...
Best result:
Vega 64 Asus Strix from 19.5 to 19.9 hk/s  L20+20

One of the "problematic" Vega56 after 30 min running got 4 rejected share invalid result too... So I have to tune this card more...
Is there any suggestion?

Power: from 680W to 705W = 25W more for rig from the wall.

CNR same settings quick run: Vega 56 got +100 H/s.

Txs Eliovp!