If you are ready to overclock the 3770K does not have to go high to equal or better the 4770. To overclock you need an after market cooler but at stock you can use the bundled cooler.
Thanks for your clarification. So a bundled air cooling is enough for 4770.
But do I need an after market cooler If I do some overclocking (not much) on 3770k?
I saw a tomshardware benchmark for 3770k and 4770k but when it comes to 4770 I don't know how much is it better and even I doubt if 4770 outperforms a 3770k in rendering. Is there any related benchmark?
Unless the benchmark stated that the CPU was overclocked, the 4770 = 4770k and the 3770 = 3770k. They are identical in every way. Same stock clock speed and same boost speed.
No, not entirely identical. But so damn close that the difference really does not matter. You can safely use a stock 4770K as an approximation of a 4770, or vice versa.