hello.if your current setup is working well you may actually decrease power consumption by swapping gtx660 with gtx 1060.
use this power calculator:
http://outervision.com/power-supply-calculator
if you calculate the power for your system and then swap the cards,you will see that 17w less is needed.so if your current system has no problems,you should have no problems after upgrade either unless the psu is not of good quality.