I'm building a pc with the primary task of gaming. I'll have quite a beefy system, but I'm not sure which CPU to get. In Australia the i7 3770k is about $40 more expensive. The 3820 leaves space for upgrade, so if they are equal, I will go with that. Also, are the any comparable AMD CPUs?
no comparable amd cpu
i will vote 3770K because of OC potential
but personally i will go with 3570K for price/performance
i dont need i7's hyperthreading
All Socket 2011 CPU's are OCable.
However, 2011 is a bit outdated, and can be expensive. The motherboard can run you a bit much, and like AMD Radeon said, you won't really use 2011's benefits. Hyperthreading only really shows its strength in Crysis 3, and a few other select games.
I would not go with the i7 3820 unless I was committed to upgrading down the LGA 2011 path when Ivy Bridge E comes out. Also, the i7 3820 and the i7 3770k are not exactly "equal." The 3770k beats it pretty much across the board in 99% of apps or benchmarks. Not by a lot mind you, but it does beat it. If you really need an i7, then go for the i7 3770k or the i7 4770k (I personally would stick with the 3770k, as I'm not convinced the 4770k is gonna be a better proc and it runs really hot).
Of course an i7 isn't necessary for a strictly gaming rig as the i5 3570k is a great gaming proc. But if you have the cash go for the i7 3770k. It wont give you a boost over the 3570k in gaming, but it will in everything else. And who games 100% of the time anyway?