I ve tried, too but I can only get two of my 4x 1070 to run, with 4 the hashrate goes down to 6-8 sols and cpu is on 100%, someone can run more than 2 Cards with high hashrate ?
Is there a Switch to reduce the high CPU usage ?
I run 3 gtx1070s with 11.5-12 S/s. Try to lower the core/mem clocks if you have them o'clocked. Also try to lower the TDP (I run them at 65-70%). If you still have issues, run 2 instances of Optiminer for every 2 cards.
EDIT: Do the mod again. Maybe you didn't do it right. I can recall this happening before applying the mod.