Low hashrate on NBMiner vs Teamredminer

Hello,

I am new to mining RVN and I was wondering if I could get some direction. I have 2 rx6600xts and 2 rx6600s in a rig I had been mining ETH and I wanted to try RVN

I used Teamredminer 1st, and it seemed to be working good. Getting 17MH/s with xts and 14MH/s with non-xts, however it would crash ALOT and not reboots but shutdown of rig. I decided to try NBMiner and have it working, seems stable, but Hashrate is 11MH/s and 7MH/s.

Any idea why the disparity and what to do to fix?