Ik overclocking does wonders getting extra juice but how bout under clocking?
Underclocking will allow you to squeeze better performance per watt ratio.
Take for example performance of gtx1080ti in equihash - @ 90-95 pl card pushes 760sols per 2.8 sol / W
@ 80-85pl card pushes 720-730 sols it is 3.1 -3.2 sol/w. and @ 65-70 pl card pushes 640-650 sols and it is 4 sol/w
The choice is yours