Unable to decide 2nd or 3rd gen

[hq56]

So I'm about 5 days away from ordering my new parts and now I'm having doubts about my CPU. My question is do I go with the i5 3570k or the i5 2500k? Things to note would be a) I'm also buying the CM Hyper 212 Evo, b) I would overclock to about 4.2Ghz (This is achievable using stock voltages, right?) and I'd like to stay below.. 70C
Basically, is it possible for me to OC to 4.2 using stock voltages without seeing any temperatures over 70C? Thanks!

 

[IntelEnthusiast]

While all processors are a little different most likely with the Intel® Core™ i5-3570K you are going to mid 70c at 4.2GHz based on my experience. While you may have lower temperatures with the Intel Core i5-2500K you would see lower real performance with it due to IPC improvements on the Intel Core i5-3570K.

 

[hq56]

So, for 'futureproof-ness', it would be wiser to go with Ivybridge. However, if I manage to use stock voltages and get a mild overclock, wouldn't that mean that temperatures would be around mid 60s to mid 70s? (I may have just rephrased what you just said, it's been a long day ) On a side note, Ivybridge can go up to around 80/85c before you should start worrying, right? Especially with a HSF, they should not be going over 76c -ish, am I right in thinking that?