MANOFKRYPTONAK :
Also I believe you can unlock a 6950 to a 6970, correct me if I am wrong and yeah i5-2500k. Get a Different PSU with a little more watts 750. AND DO NOT BUY OEM!!! ESPECIALLY WINDOWS 7, are you a student? If so buy the upgrade off of microsofts website install it then install over it you want the 64 bit version. I like full cases and I don't know much about Asrock. BUT DONT JUST LISTEN TO ME ASK AROUND AND POST THIS IN THE HOMEBUILD SECTION. You will do great, building a pc is fun, ask a lot of questions and read toms how to guides and forum how to guides.
EDIT: If you get the unlocked (K) version get the $20 insurance off of intels website.
The $20 insurance is much like every other poor extended warranty. The CPU overclocks to 4ghz without even a voltage tweak, and since it has the unlocked multiplier it makes the overclocking process incredibly easy to understand and perform, as well as making it significantly safer than oldschool overclocking (not that it was ever dangerous to begin with).
If your CPU fails for any reason other than frying it with too much voltage (which an amateur shouldn't be playing with anyway) there is no real way to prove it was overclocked. If you can spare 20 bucks, I would sooner put it into a better more reputable power supply than the intel insurance.
As far as the 6950, it was possible for a while to unlock them to 6970's, and many came with a dual bios in case anything went wrong with the process. However, most 6950's that are sold today cannot be unlocked. It's still significantly better than a 7770, but you won't likely get a 6950 that is unlockable.