i5 3570K or i5 2500K

[Madfish]

Single core performance is slightly higher. Overall I'd estimate some 7-10% gain over the 2600k.

DDR3 1600 support is kinda useless unless you're compressing files. As for gaming performance I'd rather get more RAM than faster ram. DDR3 1333 is totally fine. The gain from 1600 is way below 2% overall (various applications). In most games below 1% even.

PCIe3 support is also pretty much useless. Todays GPU's don't even profit much from PCIe2 over 1 so it's unlikely that there'll be much gain from 3.

This will probably be true even in 2013, when DDR4 might be introduced. The biggest pro the Ivy Bridge brings to the table is native USB3 and lower power consumption under load. You can save up to probably around 65% or so against a 2600k on a fine tuned system (undervolting)


All in all I'd say it depends on the budget. If you get a great deal on a 2600k go for it.