CPU comparison

Intel is better. AMD overclocks with the Base Clock, Intel overclocks with the multiplier. The only thing that matters is the end ghz, which Intel will reach a higher number than AMD.

Intel i5 3570k 3.4Gz - much, much better choise for any task
AMD FX-4100 has only 2 modules (1 module has 2 sub-cores, but it's not powerful enough as usual cpu-core), Intel i5 3570k - 4 cores
and you can overclock k-series CPU to get more performance (if your PSU can handle it)
also, FX-series CPUs has worse MHz/performance ratio than modern Intel CPUs (FX-4100 @ 4GHz ~ i3 @2.8GHz or somewhere near)
sorry, pretty bad know english(

Higher clock speed =/= better performance. It comes down to how efficiently the CPU's design can operate at a clock speed. The FX-4100 has terrible efficiency, and no matter how high you overclock it, it will fry itself to death long before it could dream of doing what a non overclocked 3570K can do.

If the price difference doesn't tell you something, than I will. the FX-4100 isn't even in the same league as the 3570K.

Actually you can´t compare an i5 3570k 3.4Gz with an AMD FX-4100 3.6GZ, though they are similar in speed. Perhaps you could compare a FX-4100 with an i3-2120, i5-2310, and i5-3450, as they are similar in CPU frequency and price.

A Core i5-3570K costs as twice as a FX-4100.

So the i5-3570K is a lot better.

Clocks are not everything...There are far more considerations of a CPU's performance. The intel will TROUNCE the fx4100.