Hi, yes it can easily run it. If it had enough PCIe connectors, it has enough amps to run two GTX 670's, let alone a single GTX 660. However you don't have enough PCIe connectors to run two 670's, you should have enough to run two 660's (Because I think a 660 uses a single 6 pin).
Your system would not be taking any more than 350-400W under load, so you have plenty of room to overclock and/or add another GTX 660, or add more HDD's/SSD's as you wanted to (Hard drives don't use much power.)
Thanks man for the great share of knowledge. i usually think that my psu VS650 is not enough but you made me think its not true.. another thing man, even i run my corsair h80i fans at 2600rpm is it ok? i have two enermax LED 120mm fans also..