WHICH ON IS BETTER AMD FX-8120 OR CORE I5 2500K IN GAMING & FOR THE FUTURE

Right now for games it would be very hard to beat the Intel® Core™ i5-2500K as the best processor for gaming. The issue is that very few games can take advantage of more then 4 threads and those that do yield very small improvements for additional cores/threads (you may get a % point or two).

Now in order for this to change something would have to happen in the compiler/programing front that makes it a great deal easier to add additional threads to the multi-threading support on the program. I have a friend that is a Ruby programer and he hates trying to program anything multi-threaded let allow trying get support for 4 or more threads out of it.

So while anything could change I don't think that the investment in the Intel Core i5-2500K could lead you wrong for gaming.

Christian Wood
Intel Enthusiast Team
 
for gaming, the 2500k is the better choice. fx has more cores but most of the new games don't even properly use 4 cores. and by the time the games utilize 4+ cores, the 8120 wont be able to keep up with then-available processors.
also you get to upgrade to ivy bridge since they're backwards compatible with lga 1155.