I'm running a 6GPU rig GTX1070's hashing good 2,655 Sol/s. Running PSU 100%.
Do I really need to change the clock settings?
Overlock GTX 1070 can increase hashrate to 510~520+ Sol/s, each card.
But it's may be unstable(crash, black screen etc.), you need to do some test, find the right settings of your card.