AnandTech took a look at a couple of power supplies in the 650W to 680W range:
Previously, we've reviewed many power supplies rated at 800W - more than even many high-end setups require. Today we want to look at a selection of more reasonable power supplies rated at ~650W, and our next roundup will have six power supplies in the 600W power range today. This range of power supply is in high demand in the market, as this tends to be where quality reaches an acceptable level without costing the proverbial arm and leg. It also helps that marketing recommends at least 600W for many "average" gaming PCs these days, so often users think they need this much power inside of their rig. The enthusiasts have moved on to designs that are even more powerful, leaving these PSUs for the mainstream markets.>/blockquote>
Check it out over here. The overall recommendation goes out to the Hiper HPU-5B680 and Xigmatek NRP-MC651 PSUs.