Big hashrate drop in ver.2.5.2
I tryed today the new 2.5.2 version with ETN mining, on hashvault. I used the official config generator, I changed the threads to 32 from 26. So the settings looks like this 32x27 6x25.
I see a new parameter "variant -1", that I understand is for a new pow... In rest, nothing changed in config or in OC.
I have 6 **GTX 1060 3GB** hynix mems, OC: power 70, temp 83, core -100, mem +500; monitor in mobo port. Win 10 x64bit, last cuda 9, nvidia drivers, vc-redist and win updates.
I get around **330 h/s**, with a total of 2010 h/s. 
With the same settings, in 2.4.5 version, I got around **480 h/s**/card, 2880 h/s in total, 3 weeks ago.
Why such a big hashrate difference? Is from the new pow? Did ETN changed the pow? 
Or the miner performs badly?