Check this guide
https://bitcointalk.org/index.php?topic=1954245.0 there is a link with well performing straps, as far as i know Uber Mix is working good only with Samsung memory (not 100% sure). Also Claymore's miner is not the best option for Cryptonight algo, try sgminer or zawawa's Gateless gate, you'll be surprised.
Good luck!
There was an update of ubermix straps (16.12.2017), now you can download good straps for hynix, elpida and micron. Actually i use it, but the problem is that adjusting cclock has no effect(
I also used zawawa's miner, the hashrate is even lower: with the best setting 700 compare to 770 that shows claymore.