GTX1060 power limit hash drop

[Zikkson]

Hello guys, o have rig with 6x GTX1060 6GB from Gainward (only available at time) and sadly all of them with Hynix memory. Im mining zcash using ewbf with +120 core +400 memory and i think something is wrong, because im facing big hashrate drop if i set lower power limit. I see many ppl here using 65% power limit almost without hashrate affected but my stats are these:
100% power - 1238sol - 538W from wall
90% power - 1216sol - 483W from wall
80% power - 1179sol - 430W from wall
These stats are taken from 4 cards, anither 2 cards are off for now.

I played with one card and at 100% power it produced around 312sol and at 65% power it dropped to 260sol. While i oc cards core clocks oscilating 100mhz up and down by the way.

Is that normal or i have some wrong config?

Mobo: msi z270 gaming plus
Psu: corsair 750w gold
60gb ssd, 4gb ram, celeron g3930, windows 10 (1703), latest nvidia drivers 390.65

[0xcosmos]

it is normal
zcash requires more core and more power
if you reduce power limit hashrate will be affected

[papampi]

Try DSTM ZM miner, gives much more