For those, who need comparison data and interested in Claymore miner progress 
power of the wall
vX - version of Zcash miner
-i 6
GPU v8 v7 v6 v5 v4 v3 v2 Power on v8
7870 115 95 65 55 40 35 32 110w
7950 190 155 125 95 70 45 38 140w
7970 200 165 120 95 65 55 48 150w
270x 115 100 67 55 40 35 32 100w
280x 200 165 125 90 65 60 51 100w
285 125 110 85 70 40 36 32 165w
RX 470 4Gb 180 155 145 120 70 60 50 120w
power of the wall
vX - version of Zcash miner
-i 6
GPU v8 v7 v6 v5 v4 v3 v2 Power on v8
7870 115 95 65 55 40 35 32 110w
7950 190 155 125 95 70 45 38 140w
7970 200 165 120 95 65 55 48 150w
270x 115 100 67 55 40 35 32 100w
280x 200 165 125 90 65 60 51 100w
285 125 110 85 70 40 36 32 165w
RX 470 4Gb 180 155 145 120 70 60 50 120w
How did U get 200 sols with 100W from 280x? Mine takes about 140 and it's already undervolted.