The bare minimum you can go with is 550 watts, at 100% your GTX 670 SLI and 3770k with 16gb of ram uses 494 watts, include a DVD Drive, and hard drive and you should just reach 550 watts. I would recommend you go a bit over just in case and settle with a 600 watt power supply. Remember to keep your power supply brands to be high quality like Antec, XFX, Seasonic, PC power and cooling, Corsair, Enermax etc.
Here is one example:
*note there will not be a power cord with this, I assume you have one if you have older computers or built others before.http://www.newegg.com/Product/Product.aspx?Item=N82E16817371031