I honestly can't understand why , with a new build and a i5-2500k cpu would you want a video card like that , do you not have a good enough budget amount to get a better card? Can you change the order and get a better video card? That build should have a minimum 6850 and it should have a 6870 or 6950.
Yeah I was going to , but atm it is a budget constraint. trust me.... I will not be doing that much gaming. But at the same time with the 7xxx series releasing, I can hold on with the card and not worry until then.
A lot happened which resulted in me getting the card in the mean time, otherwise I would have gotten a 6970.
Artic Silver 5 is the proven standard as the best thermal compound.
As far as fans go there are so many to choose from that in the end you almost can't make a mistake , one thing you can do is look at the cfm and get the better airflow to the lowest noise db ratio. You don't want something that sounds like anairplaneinside your case.
There is nothing wrong with the hyper 520 it has two fans and offers a better cooling solution than the 212 evo.
On the psu I would go with the Antec , Seasonic or Corsair.
The case is more of a persoal choice because it has to be something you like , but at the same time you want to make sure it has enough room inside.