RTX 3070Ti Ravencoin - inconsistent hashrate

Hi there , before over a month I assembled new rig - 1x6800XT , 2x3060ti LHR and 2x3070ti.
3060ti’s are going ok with 28-29Mh/s , 6800XT is on ETH but i have some problems with 3070ti’s
Here are my results

And settings

Problem on 70ti’s is that hashrate is inconsistent, when i restart my rig hashrate is ok for 5-10 minutes, then became to drop above 39-40Mh/s then againg rises to 41 and. When hashrate drops i see that and power consumption too drops because i set 260 PL but it goes 240W and lower along with hashrate.
If card is throttling(i forced it with lower fan speed) hashrate drops notably to 33-34Mh/s so i exclude that this drop in hashrate is from thermal throttling, because hashrate drops from 41 to 38-39Mh/s
I consider that LHR limiter is messing around , but problem is only on 70ti’s , on 60ti’s hashrate is consistent - 28 adn 29Mh/s which is strange.
Hope if someone face with this problem and help to solve it. This video is interesting and close to my problem.

Cheers !