Intel Core i5 2500K 3.3Ghz or AMD FX Series FX-8350 4.0Ghz 8X

if your going to be gaming and rendering get the 8350

http://www.anandtech.com/print/6396

http://www.hardwaresecrets.com/printpage/FX-8350-vs-Core-i5-3470-CPU-Review/1657

The i5.

2.5k i prefer

If going applications / graphic processing, then the AMD FX...

The i5 for gaming performance with an Ivy Bridge motherboard, I would however suggest the non-k version (unless your overclocking and going Sandy Bridge). You could get the i5 2600 or better, a good graphic card such as the GTX580, GTX660TI or better, then you have yourself a 2nd or 3rd generation gaming pc (60-80% performance increase over first generation)!

For rendering and multithread app AMD FX 8350, for gaming a good vga ;)
AMD FX-8350 and Intel i5 2500k comparison

I don't know what kind of rendering are you after, but giving these two choices, i'd go straight for the I5, if you want to do some heavy rendering (or you're planning to use it more for rendering than gaming, and want to go for some fast times), then go for the 8350, or something a bit beefier on the AMDFX line, or just go straight for the I7 series.

intel if you want a renderer

Get a 3570K instead.

Both will do well, i5 will do better in gaming.

Not sure how much an advantage the AMD would be in rendering.

Do you have a graphics card, if so which one?

If the answer is no, then the FX-8350 would be the better choice. If you plan on buying a GPU, then the i5 2500k would be the better choice.

EDIT: Damn, too many people beat me to posting, chances are you won't get correct information now. :(

Sorry if this sounds undermining of your knowledge; you do know that most motherboards only support Intel or AMD, and very few support both? I just want to make sure, as you did not make any mention of a motherboard. I'm assuming you know this though.

My answer to you is this.
It depends on the price. Rendering and gaming currently are mostly dependent on your GPU. (Unless you are doing software rendering.)
So get a Good GPU.

AMD's high end FX processors are rubbish, the low end FX-4100 is okay for the price. First, most of the new games only fully utilize 3 cores, except GTA IV and Borderlands 2 to a lesser extent. Second the FX processors are not energy efficient. Third Intel i5 is better in games, the FX bottlenecks in Metro and Skyrim.

http://www.tomshardware.com/reviews/fx-8350-core-i7-3770k-gaming-bottleneck,3407-3.html

However in the future, about the year 2020 games will fully utilize 8 core and FX may be better. Also Playstation 4 and Xbox 720 is rumored to have 8 core AMD cpus so console port games may become better optimized for AMD.

http://kotaku.com/5977849/the-playstation-4-has-a-new-controller-fancy-user-accounts-and-impressive-specs-so-far

I think FX8350 is better.

intel

i5 2500k ofc.

why would u want a 2500k instead of 3570k ?

i5 2500k,but still why don't you go for 3rd generation i5?

AMD FX 8350 OC vs i5 3570k OC