How much power do I need for my PC?

the p2 650w is $100 really before rebates,for that price upfront you can get a 750w g2 & for that reason I see no reason not to.
the 650w is 'probably' enough until in the future you decide to push your overclock more & maybe bump up the 980ti clocks a bit too & then youll be on the edge again where you are now.
 

Dark Lord of Tech

Retired Moderator
650W is plenty for that current setup.

Intel Core i7-4790K 4.0GHz Quad-Core Processor 11W - 88W
NZXT Kraken X61 106.1 CFM Liquid CPU Cooler 10W - 15W
ASRock Z97 EXTREME6 ATX LGA1150 Motherboard 17W - 70W
G.Skill Ripjaws Z Series 16GB (4 x 4GB) DDR3-1600 Memory 18W - 18W
Samsung 850 EVO-Series 500GB 2.5" Solid State Drive 2W - 10W
EVGA GeForce GTX 980 Ti 6GB Superclocked+ ACX 2.0+ Video Card 62W - 250W
Total: 120W - 451W