Bit of an overkill in my opinion since 750 watts is usually recommended for crossfire/sli systems which means 2 video cards. I believe you should be fine with a quality 550-600 watt power supply with more than enough room.
You think that's overkill, I'm using an 850W on my system! Look to the future, the last thing you want is making the decision to SLI the cards or upgrade fully and need to spend more on another PSU. Also, the XFX core series PSU's are excellent (I have the 850w version.)
Lol look at my system and my PSU. It's not a bad idea to buy more power, espically if you get a long warranty with your PSU, never know if you might come across a really cheap card later on for a Crossfire setup. Just make sure your still buying a quality unit though, quality is more important than extra power for sure.
Well 650 watt power supplies is more than enough with ample headroom for future upgrades.
The 3570k consumes around 75 watts (probably less than that)\
GTX 670 uses around 170 watts
Those two major power drawing components don't add up to be very much.
However no harm done getting a bigger power supply but truth is you will be wasting more money on it when you wont use it. Generally the trend with most video cards is they get more efficient with each new series.