I wouldn't buy 1.65v ram, it's not too good for Sandy Bridge.
To be honest, for a gaming PC a 2500K is all you need. The extra cores/memory bandwidth is wasted on games and will not give you any additional performance.
And unless you are planning on adding another 680 in the future, a 1kW PSU is massive overkill. A good quality 650W will be absolutely fine.