Overclocking i5 6600k and GTX970. Recommended Wattage?

[Nqs Blackout]

Alright so Im building a pc and I want to OC my i5 6600k processor to 4.5Ghz (stock 3.5) I'm getting a be quiet dark rock 3 cpu cooler and my current psu is 650w. Here's the build http://pcpartpicker.com/user/RushCAT/saved/gkKmP6 What Im trying to ask is should I get a better PSU to make the overclocking possible/safe. P. S. My budget is only $975

 

[Sapphire Thunder]

600W PSU is pretty much what you will need with moderate overclocks.
BUT: EVGA SuperNOVA Nex is a bad, Tier 4 PSU. You will need to change that.

http://pcpartpicker.com/p/D3YQ4D

Here, better and cheaper PSU + cheaper cooler.
be Quiet Dark Rock 3 isn't all that good for the price.
Cooler Master Hyper 212 EVO is almost exactly as good and costs more than 50% less.

So with these changes you get better psu and lower price without losing much cooling power.

 

[Nqs Blackout]

600W PSU is pretty much what you will need with moderate overclocks.
BUT: EVGA SuperNOVA Nex is a bad, Tier 4 PSU. You will need to change that.

http://pcpartpicker.com/p/D3YQ4D

Here, better and cheaper PSU + cheaper cooler.
be Quiet Dark Rock 3 isn't all that good for the price.
Cooler Master Hyper 212 EVO is almost exactly as good and costs more than 50% less.

So with these changes you get better psu and lower price without losing much cooling power.

What's the most I could OC and still keep temps safe on full load?

 

[Sapphire Thunder]

Hmm...I would say 4.2 or 4.3Ghz with Hyper 212 EVO.