http://pcpartpicker.com/p/rfnHXLA small concept build I put together for you, for the parts that you requested, going just slightly over your $500 budget.
i5 4690 still a great CPU in single core performance, and is going to benefit you a lot. Not unlocked, like requested. If you want to take advantage of the hyper-threading that i7s offer, you'd have to spend a little bit more, but nothing too drastic.
ASRock H97 PRO 4, great budget motherboard, gets the job done. Cannot overclock a CPU on it, as requested. Expansion is limited in terms of the GPU side of things, so if you plan to SLI / Crossfire, you may want to reconsider.
Simply 8GB 2x4 RAM. Shouldn't need more than that. If you're serious about the rendering, and video editing, and are dedicated towards it then go ahead and opt for 16 gigs.
Finally, 960 is a great budget CPU. The 970 is quite a bit more powerful, but so is the cost for this budget. However, it will get the job done very well, and will certainly play modern games at medium settings.
