I have a few Vega 56 Airboost cards (hynix memory) in place. Unfortunately the seems to be weaker than all others. No timinings are working stable currently which I have been able to found. Somebody had the same problems like me and got maybe a little bit further?
I have 3 rigs running MSI Airboosts, 6 per rig, I finally managed to get these bad boys stable for a few days at a time, i manually restart the machines every 2 - 3 days so i dont know if these setting are stable any longer, in 2 - 3 days i get 1 or 2 HW issues MAX usually none. I agree with you, i feel that these cards are the worse out of all the vega's.
Give this a try.
Name=Vega56
GPU_P0=852;800;0
GPU_P1=991;800;0
GPU_P2=1084;800;0
GPU_P3=1138;800;0
GPU_P4=1150;800;0
GPU_P5=1202;800;0
GPU_P6=1407;800;0
GPU_P7=1407;875
Mem_P0=167;900;0
Mem_P1=500;900;0
Mem_P2=800;900;0
Mem_P3=875;900
Mem_TimingLevel=1
Fan_P0=30;70
Fan_P1=50;70
Fan_P2=58;70
Fan_P3=67;70
Fan_P4=75;70
Fan_ZeroRPM=0
Fan_Acoustic=2400
Power_Target=0
--RAS 24 --RCDRD 19 --RCDWR 4 --RC 35 --RP 13 --RRDS 4 --RRDL 5 --RFC 148 --REF 15600
--cn_config=14*14
https://i.imgur.com/iQGbqhM.jpg