Gaming PC computer around $1000-1500 Aus

I would cut the 16GB of RAM down to 8GB unless you specifically need it. Also, a higher end graphics card might not be so bad at your budget, something like a 7950 since it OCs like crazy (I personally own 2 and they are amazing cards), comes close to a GTX680 even.

RE the PSU, if you're planning on staying with a single GPU config then a good quality 600W PSU is more than enough, even for some heavy OCing. If you're planning to go SLI or CF, then perhaps a 800W PSU would be good. In either case, get a very good quality one, look for 80+ certs and all that. A PSU is not something you should cheap out on.

Cool thanks for the reply, is there a good quality 800W power supply that you recommend?

I would get a Corsair or Seasonic PSU
PLus i would change the i7 3770k down to a i5-3570k
I would get a AMD HD7950 or GTX670 graphics card
You will only need 8gb of ram for gaming but 16gb is cheap enough so u can happily get 16gb for very little price difference

What's the price difference between 660 ti and 670?

Average Aussies prices from where i buy stuff is $325 cheapest 660TI , cheapest GTX 670 is about $435
So your looking about an extra $100 to move up to a 670

Theres a CORSAIR HX Series HX850 850W and CORSAIR HX Series HX750 750W
Both 80+ gold certified.
Which one would you prefer if I had all these parts i've selected.