LeadTek WinFast GTX680 4GB how far would it goes?

Guys.

A local website in Malaysia is selling a combo on LEADTEK WinFast GTX680 (4GB ver) c/w Seasonic 80+ GOLD 660W modular PSU price tag is around USD550 (promo).

question:

1. The GPU + PSU = worth it?

Other info:

1. I would OC it, but cant found any drivers on the website maybe it comes together (stability unknown)
2. If I recall its a reference design with dual slot heat sink (noise and temp = unknown)
3. Currently in my country its the cheapest combo sale so far which c/w a gold rated PSU.
4. Would go for water cooled GPU. (is there any diff layout for 2GB ver and 4GB ver)
5. As I recall LeadTek produce product for high end graphics solution for workstations.

Would Appreciate Your helping fingers to reply me