First - quick results for cn-trtl, w/ efficiency-focused settings, using timings mostly borrowing from others here, w/ some minor tweaks:
Vega 64 air, ubuntu 18.04 + amdgpu-pro 18.50, TRM 0.4.3 (L18+18), 852 cclock (p0)/1107 mclock/818mv, power readings at the wall
stock timings:
--CL 20 --RAS 33 --RCDRD 16 --RCDWR 10 --RC 47 --RP 14 --RRDS 4 --RRDL 6 --RFC 260 (--REF 3900)
18.5 kh/s @ 135w (137 h/w)
modded timings 1
--CL 19 --RAS 28 --RCDRD 12 --RCDWR 5 --RC 44 --RP 12 --RRDS 3 --RRDL 3 --RFC 248
19.75 kh/s @ 137w (144 h/w)
modded timings 2
same as above, plus --REF 15600
20.71 kh/s @ 137w (151 h/w)
What bios are you using . I can get 20.1khs per card but have to run 1250 core 1100mem using 145w
Edit
Managed to get it to 21.8 khs @ 125w in hwinfo pulling 1060w from wall with 6 vegas approx 130khs trt