Take back on intensity or overclocking, you are producing bad shares (share above target).
intensity default
overclocking same as claymore and phoenix and work fine with better hr\power wihout bad shares
stat from claymore miner
ETH - Total Speed: 373.770 Mh/s, Total Shares: 132(6+10+18+7+7+12+9+16+14+11+10+12), Rejected: 1(0+0+0+0+0+0+0+0+1+0+0+0), Time: 00:44
ETH: GPU0 30.484 Mh/s, GPU1 31.325 Mh/s, GPU2 31.294 Mh/s, GPU3 31.325 Mh/s, GPU4 30.800 Mh/s, GPU5 31.336 Mh/s, GPU6 31.281 Mh/s, GPU7 31.268 Mh/s, GPU8 30.813 Mh/s, GPU9 31.250 Mh/s, GPU10 31.333 Mh/s, GPU11 31.259 Mh/s
Incorrect ETH shares: GPU0 1
1 minute average ETH total speed: 373.612 Mh/s
Pool switches: ETH - 0
Pool shares accepting time (1 hour stats) - min 31 ms, max 375 ms, average 58 ms
Current ETH share target: 0x000000007fff8000 (diff: 8590MH), epoch 0(1.00GB)