I'm getting 28+ if I go up to 150+ watts I guess too.  The cards hash fine, they just don't have a good Mhs/Watt for Dagger compared to my other cards.

They use too much power and don't come with additional hash power to compensate.  Better for Cryptonight than Dagger for sure.

I also have a RoG Strix 1080 ti and it overclocks for shit compared to some other high end brands.  I guess they probably bin the Posieden for their best silicon.