Well i'm planning on building my first pc, so i've already bought everything but the GPU, i'm not sure which to buy.
So i saw the PNY 770 2gb from $330 to $290 and the EVGA 760 SC 2gb from $260 to $250
and i have a budget, does the 770 really worth it?
If you are comfortable with the higher price, buy the 770. You will see some definite performance improvement over the 760. However, make sure your CPU will not bottleneck the card.
i didn't even knew what is bottleneck (i kind of know now) but how can you know if it bottlenecks it is an i5 4670k
Well, it's as simple as looking at some numbers and a bit of research to find out if a bottleneck is going to occur. But to answer your question, no, you shouldn't see any bottlenecking as far as either card goes.