I5 2500K or i5 3570K for OC'ing

2500K, ivybridge is a joke.

I'm with muffin.

ok, ive been researching a few reviews about this topic, but i always get confused because some say ivy's OC is hotter, ivy is better core for core, etc2...

so, what is it that ivy lags behind sandy when it comes to OC?

Apparently Intel changed the TIM on the Ivy Bridge CPU's. They used some thermal paste instead of the solder they used on SB, which in turn increased heat significantly reducing overclocking headroom.

IB chips ARE faster clock for clock, however, but it's not worth purchasing if you're an avid overclocker due to its heat.

Some people have gotten lucky, however, and have reached over 4.8Ghz with their IB chips.

http://www.techpowerup.com/164858/Ivy-Bridge-Temperatur...

"PC enthusiasts with Ivy Bridge engineering samples, and reviewers at large have come to the consensus that Ivy Bridge is a slightly warmer chip than it should be. An investigation by Overclockers.com revealed a possible contributing factor to that. Upon carefully removing the integrated heatspreader (IHS) of an Ivy Bridge Core processor (that nickel-plated copper plate on top of the processor which makes contact with the cooler), the investigator found common thermal paste between the CPU die and the IHS, and along the sides of the die.

In comparison, Intel used flux-less solder to bind the IHS to the die on previous-generation Sandy Bridge Core processors in the LGA1155 package. "

for what it's worth, the 2500k OCs higher, but as we know clock speed isn't everything (cough AMD) -- IPC is important and ivy is better in that regard.

^ But don't forget they didn't do any major archetectural changes besides shrinking the die from 32nm to 22nm, it's only around 5%-10% faster clock for clock, not very significant considering most Sandy's are hitting around the 5Ghz mark. Ivy's tend to cap around 4.5Ghz-4.6Ghz = 4.8Ghz-4.9Ghz Sandy.

so, basically what all these means; ivy have smaller number of OC clock speed compared to sandy,

but ivy's smaller number OC clock speed is equal to sandy's bigger number OC clock speed?

Basically yes, depends on the clock, but yes. For example -

i7 3770k @ 3.5Ghz vs i7 2700k @ 3.5Ghz

The i7 3770k will be faster than the i7 2700k due to it's higher IPC. Once you overclock, however, I say that the higher IPC on Ivy is irrelevant.

well, as a minor overclocker, 4.2 ghz on my i5 2500K;

i got to say, ivy is more appropriate for me at 4.2 ghz...  

Yes, I suppose it is more appropriate if you're only to OC it a little bit. However, why don't you push your 2500k to 4.5Ghz? It's known to hit that frequency with around 1.3v   should be no sweat if you have a decent cooler.

i can reach 4.5 ghz, cuz i have hyper 212 evo, but, my Gigabyte Z77M-D3H mobo has no vcore manual settings.

it is locked on auto... hehe, budget build bro, cuz this mobo only costs me around $97.. out of stock in newegg now..  

Ooooh I see   Auto voltage...yeah I wouldn't trust that too much

it's ok bro, 1.2v for 4.2 ghz, stable prime 95 for 26 hours, and...... 63C on max load too...

+1

Ivy and a z77 is a good match. Some modest advances... pci 3.0. I only OC to 4.2 because I want it to last 10 years. Oh stock cooler too...

honestly both classes are fast and easily overclocked. No one could tell the difference unless benched.

Oh wow that's not too bad