The problem is my power limitation. I have 1000w Cooler Master Gold 80+ (with 4×1070) and at this power I cant overclock.
No way. At the most you would probably pull 650W at the wall ...unless you are running other peripherals I am unaware of.
I highly suggest getting a kill-a-watt meter from Amazon or newegg or wherever. You can find them around $20 and well worth it. I have one on each mining rig to monitor my power consumption.
ps. a little while ago I called evga about their power supplies, and asked Jose from EVGA how much can I pull constantly from the supply safely. He suggested 80% of max rating. Going my that theory, you could safely pull 800W constant without worry.