bob hays :
Yes even with the overclock I believe that the i5 would beat the 8320 in gaming. And remember to overclock you have to add the cost of cooling and power.
not true. Depends if you're going off the THG cpu benching suite of Civ 5, Skyrim and Far Cry 3 or not... if you're just looking at those 3 titles, and that fx8320 isn't clocked over 4.4ghz, then when you say is true. However, once you clock a 6 core fx up to 4.8ghz the difference between it and a STOCK i5 is less then 5% on average across multiple gaming titles.
here is a look at the proof; note, in this example we're looking at a fx6350 clocked to 4.5ghz... if you were to further clock it to 4.8ghz, the difference between it and the stock i5 would be indistinguishable (it would actually hold a slight lead)
Generally speaking an overclocked to 4.8ghz fx 8 core will regularly perform a bit faster then any stock i5...
That said, the overclockable i5s will leave that fx8 core in the dust... however the OP didn't present an overclockable i5 as a purchasing option. so what i said is 100% true. If he's planning on overclocking, that fx8320 is the best option on the table. if he is not, that i5 is.