How big should my power supply be?

[CStretch]

So here is the setup I am planning on doing, but the only question I have is how big should my power supply be? Im not really sure, and I dont want to go overkill and pay too much if I dont have to. Thank you for any help.
Mobo: ASUS Maximus VIII Hero Extreme RTL Configurator
CPU: Intel I7 6700K 8M Skylake Quad-core 4.0 GHz
RAM: G.Skill Ripjaw V Series 64 GB (2x16GB) DDR4
HDD: Seagate Desktop HDD ST2000DM001 2TB 64MB
SSD: Samsung 850 EVO 500 Gig SATA 3
GPU: Dual GTX 970 FTW 4GB
Cooling: Coolmaster hyper D92

 

[Bravionic]

So here is the setup I am planning on doing, but the only question I have is how big should my power supply be? Im not really sure, and I dont want to go overkill and pay too much if I dont have to. Thank you for any help.
Mobo: ASUS Maximus VIII Hero Extreme RTL Configurator
CPU: Intel I7 6700K 8M Skylake Quad-core 4.0 GHz
RAM: G.Skill Ripjaw V Series 64 GB (2x16GB) DDR4
HDD: Seagate Desktop HDD ST2000DM001 2TB 64MB
SSD: Samsung 850 EVO 500 Gig SATA 3
GPU: Dual GTX 970 FTW 4GB
Cooling: Coolmaster hyper D92

I think you'd be safe with 700-800w.

Edit: I recommend going with a Corsair PSU. I've got one and from what I hear they are very reliable.

 

[Geekwad]

~750w is good for wattage:

http://www.realhardtechx.com/index_archivos/Page362.htm

But don't skimp on the quality:

http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html

For a stable gaming platform that will perform flawlessly for years to come, Tier 1 & 2 PSUs are recommended.

 

[rolli59]

So single GTX970 system needs 500watts! Basically any 500watt or bigger quality unit will run it fine. I have almost the same system running on EVGA G2 550watt!
http://www.realhardtechx.com/index_archivos/Page362.htm

650 watt unit great price http://pcpartpicker.com/part/evga-power-supply-210gq0650

 

[Dan414]

Why skimp on the PSU? You're clearly not sparing the coin elsewhere. Get a nice supply to protect your nice components.