I5-3470 + 7950 3GB VS i5-3570K + 7870 2GB

3470 + 7950. better. i5 3470 can handle any games jsut like the 3570k.

If the 3570K is overclocked to about 4.2GHz, will it make a huge difference in gaming? Or would the difference be larger between the 7870 and 7950?

If your motherboard and power supply would be sufficient for Crossfire, I would go with the 3570k, which is actually very easy to overclock. 4.5GHZ can be easily achieved with minimal knowledge now days.

Then when you have the money for a second 7870, crossfire them for a beastly gaming PC.

you can overclock the non k processors with some programs I don't remember. (i think)

No you cant



The 7950 and 7870 perform reasonably closely , but once overclocked the 7950 is way better

Get that and the 3470 IMO
Overclocking a processor wont do a lot for gaming

The i5-3470+7950 is cheaper too because of the savings on a cpu cooler, unless its possible to get a decent overclock with the i5-3570K stock cooler, is it possible?