Advice on budget gaming computer upgrade

Approximate Purchase Date: 1 month
Budget Range: 400-600 USD After Rebates
System Usage from Most to Least Important: Gaming, movies, some 3D modeling
Parts Not Required: All peripherals, PSU (Silencer S75CF 750W), case
Preferred Website(s) for Parts: Newegg, but I am not terribly picky
Country: USA
Parts Preferences: none
Overclocking: Yes
SLI or Crossfire: No
Monitor Resolution: 1440x900
Additional Comments: none

Upgrading the "guts" of my old PC. My goal is to build a gaming computer that will last ~4 years as inexpensively as possible. I've selected parts I think would be suitable, and am looking for tweaks/suggestions/GIANT MISTAKES I HAVE MADE.

Motherboard: ASRock P67 PRO3 (B3)

http://www.newegg.com/Product/Product.aspx?Item=13-157-...

Pretty cheap, several reviews mention positive results doing what I plan to. I'm fairly focused on gaming, and this seems to cut a fair amount of features that would go unused in favor of a lower pricetag.


CPU: Intel Core i5-2500K:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I see a lot of recommendations for this, and some solid results. My main concern is that between the CPU itself and the fan I'd need to purchase for OC'ing, that's an additional $60 for what seems like a fairly marginal performance increase over the i5-2400. I guess the question here is... is it worth the pricetag?


Fan: Cool Master Hyper 212 Plus

http://www.newegg.com/Product/Product.aspx?Item=35-103-...

I'm not planning on going crazy with OC'ing (aiming for 4GHz), and this seems like it will be able to handle that. I've not heard a specific confirmation that it will fit on the motherboard, but I did see a review of someone using an EVO (which has almost the exact same dimensions) without any issue.


GPU: XFX HD-687A-ZHFC Radeon HD 6870 1 GB

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Again, solid reviews, solid benchmarking. I'm also considering a 5850 as its performance appears only marginally inferior, while selling for around half the price (though I suspect longevity will become a Thing in that case).


RAM: Kingston HyperX TI Series 8 GB (2x4GB) PC12800

http://www.newegg.com/Product/Product.aspx?Item=20-104-...

Solid reviews, relatively cheap. Nuff said. I did look at a couple GSkill Ripjaw X Series, but I couldn't see any difference and they were more expensive.