Not if your power supply is a good quality unit. The suggested capacity for the 2070 series cards is much the same as for the GTX 970. Less in fact.
Would you consider SeaSonic - FOCUS Plus Gold 550 W 80+ Gold Certified Fully-Modular ATX Power Supply, a good quality unit?
Here is a link to it on amazon. http://a.co/d/1A2WEnx