I have configured 40+ GPUs achieving 30.0-31.9 on cards with 140-150W on wall per card on ETH only mining.
I use my own approach in dealing with the wiring/bios/modding/running Claymore and setting the undervolting/underclocking values for each card individually. Each card is different so it needs to be tuned individually.
As as see many newbies challenged with the setup I am offering my assistance to anyone willing to match my results.
If you are up for a test drive, I would be willing to help you tune your system directly to a similar results to mine (see below). Done this few times using Skype/TeamViewer - works great.
Send a request via PM.
Next is my current status report from Claymore 11.0 (in total running 1.25GH/s stable):
Rig number #1: 13 cards all ASUS ROG STRIX TOP or OC Edition 8GB with Hynix and some with Micron memory.
ETH - Total Speed: 406.426 Mh/s, Total Shares: 2693(198+209+191+216+211+196+228+203+229+175+202+232+203), Rejected: 0(0+0+0+0+0+0+0+0+0+0+0+0+0), Time: 07:48
ETH: GPU0 31.390 Mh/s, GPU1 31.593 Mh/s, GPU2 30.882 Mh/s, GPU3 31.742 Mh/s, GPU4 31.531 Mh/s, GPU5 31.208 Mh/s, GPU6 31.385 Mh/s, GPU7 30.805 Mh/s, GPU8 31.374 Mh/s, GPU9 31.385 Mh/s, GPU10 31.385 Mh/s, GPU11 31.048 Mh/s, GPU12 30.697 Mh/s
Incorrect ETH shares: none
1 minute average ETH total speed: 405.764 Mh/s
GPU0 t=49C fan=0%, GPU1 t=52C fan=33%, GPU2 t=51C fan=32%, GPU3 t=52C fan=0%, GPU4 t=51C fan=0%, GPU5 t=51C fan=0%, GPU6 t=51C fan=31%, GPU7 t=51C fan=31%, GPU8 t=51C fan=0%, GPU9 t=50C fan=31%, GPU10 t=51C fan=0%, GPU11 t=53C fan=32%, GPU12 t=54C fan=27%
Rig number #2: 13 cards: 9x - ASUS ROG STRIX TOP or OC Edition 8GB with Hynix and some with Micron memory, 4x Gigabyte Nvidia 1070 8Gb (GPU9-12)
ETH - Total Speed: 399.940 Mh/s, Total Shares: 7300(564+614+570+560+563+528+555+548+516+598+544+555+585), Rejected: 1(0+1+0+0+0+0+0+0+0+0+0+0+0), Time: 21:37
ETH: GPU0 30.641 Mh/s, GPU1 30.595 Mh/s, GPU2 30.793 Mh/s, GPU3 30.613 Mh/s, GPU4 30.753 Mh/s, GPU5 30.554 Mh/s, GPU6 30.600 Mh/s, GPU7 30.649 Mh/s, GPU8 29.419 Mh/s, GPU9 31.323 Mh/s, GPU10 31.323 Mh/s, GPU11 31.354 Mh/s, GPU12 31.323 Mh/s
Incorrect ETH shares: none
1 minute average ETH total speed: 399.767 Mh/s
GPU0 t=53C fan=33%, GPU1 t=51C fan=31%, GPU2 t=50C fan=29%, GPU3 t=51C fan=31%, GPU4 t=50C fan=31%, GPU5 t=52C fan=38%, GPU6 t=51C fan=32%, GPU7 t=50C fan=30%, GPU8 t=50C fan=0%; GPU9 t=63C fan=49%, GPU10 t=66C fan=54%, GPU11 t=61C fan=45%, GPU12 t=63C fan=48%
Rig number #3: 13 cards all ASUS ROG STRIX TOP or OC Edition 8GB with Hynix and some with Micron memory.
ETH - Total Speed: 411.677 Mh/s, Total Shares: 11652(895+845+871+858+942+892+896+924+904+942+891+887+905), Rejected: 1(0+0+0+0+0+0+0+0+0+0+0+0+1), Time: 33:36
ETH: GPU0 31.817 Mh/s, GPU1 30.646 Mh/s, GPU2 31.593 Mh/s, GPU3 31.901 Mh/s, GPU4 31.941 Mh/s, GPU5 31.939 Mh/s, GPU6 30.881 Mh/s, GPU7 31.951 Mh/s, GPU8 31.960 Mh/s, GPU9 31.951 Mh/s, GPU10 31.951 Mh/s, GPU11 31.388 Mh/s, GPU12 31.757 Mh/s
Incorrect ETH shares: none
1 minute average ETH total speed: 411.193 Mh/s
GPU0 t=52C fan=33%, GPU1 t=51C fan=34%, GPU2 t=49C fan=0%, GPU3 t=53C fan=0%, GPU4 t=51C fan=0%, GPU5 t=50C fan=29%, GPU6 t=50C fan=0%, GPU7 t=50C fan=0%, GPU8 t=52C fan=0%, GPU9 t=49C fan=0%, GPU10 t=50C fan=0%, GPU11 t=54C fan=30%, GPU12 t=52C fan=30%
BTW: One of my ongoing projects is creating autotune tool to individually tune the -dcri option in Claymore. Will share results/tool when complete.