Its better to set power limit all the way up it will help stable the gpu in general (card will only use more if needed but gpu will not go full power just by turning it up full) . Then do your undervolt . Start at 1100 and work your wway down in small steps (like 1150 , 1125, (good start at) 1100 , then try 1095 , 1090 , etc and see how that works for you . ~ Gpu should run cooler but stable while still only using the basic power it needs depending on your usage (game settings etc) .
