I purchased and built a computer a few months ago and have been getting a few hiccups in ACIII and WOW, so I decided it's time to overclock the processor. My products are those stated in the TT and linked above. I'm currently overclocked at 4.0 GHz and 1.230V running Prime95 (which I don't know how to tell if I get an error, I assume it'll just have a line saying error too hot or something similar). I tried OC'ing at 4.4 GHz and 1.23V at first but the PC crashed a few times. So now I'm trying to find the sweet spot to overclock with no errors, and any help would be appreciated. I understand the basics but I don't know how I should go about monitoring Prime95. I'm currently running the Prime95 stress test on the default option (not high end, not custom) and the 512 self-tests have all passed so far after about 15 minutes of usage. I feel the voltage may be too high and the overclock may be too low.
As always, it depends on the chip. I would start at 1.25 personally (and if stable, try slightly less voltage). I am running the exact same mobo and i5 (have a cheaper cooler though).
I am pretty sure you can get it to work at 1.25 if you set the LLC at the right setting, and possibly disable throttle and power saving options as needed. Ivy bridge are a bit touchy, but with the right tweaking a 4.4 ghz OC on air is quite feasible.
See the Tom's recent system builder 2000$ performance pc for BIOS settings.
And PS, make sure to run the most recent BIOS etc.
Edit : One last note - temperatures will be your inhibitor before voltages will. 4.4 ghz is the sweet spot for most people, but once again depends on the chip. Try setting the LLC at medium and disabling all throttling / power saving options with 1.25 V first off - and find your threshold. If you can get it stable there, then try tweaking other options and putting the power saving options back on (EIST is a really nice feature when your CPU is idle half the time anyway).
Needless to say, the Ivy Bridge chips see extremely touchy. 4.4 ghz on air is probably the max I will ever push my chip, and it takes lots of patience tweaking BIOS settings to optimize your OC.
The chip is super fast though, I'm incredibly happy with it, and very happy I chose IB over sandy bridge... It's a faster piece of hardware! (I am and always have been a single GPU guy)
Update since I have found my sweet spot:
Z77X - DS3
CM 212 EVO
4.4GHZ @ 1.235V, 1.700 VCCPLL, LLC Medium
All power savings options ON!
Stable AIDA64 11 hours 49 minutes as I type this text.
According to AIDA64 My temps during this test are averaging high 50C, one core has spiking to 75C on AIDA, 76C on Core Temp.
16GB Ram 10-10-10-27 @ 1.5V (and I will NEVER overvolt my Ram)
Turned the CPU Fan control OFF in Bios (so it runs full speed constantly)
I copied the Tom's Hardware 2000$ system build Bios settings exactly for other settings.
PS I was not stable @ 4.4ghz @ 1.23 volts. 1.235V was exactly what my CPU wanted with LLC (Vdroop) at medium.
Since you have a better cooler you might try 4.4GHZ somewhere between 1.20V and 1.25V, and if you are stable, work down from there.
You should always run Intel Burn In Test also to check and see if it crashes. My PC runs 10c cooler with prime95 and prime95 never crashes my PC. So if you really want to see if your cool and stable, run Intel Burn In Test.
Thanks for the best answer, but I have a confession to make. I found out about WHEA errors in the Event Viewer, and my OC was definetely NOT stable at 1.235V. As a matter of fact, I had some games crash shortly after writing my post.
I ended up settling for 4.3GHZ @ 1.240V. This eliminated my WHEA errors.
I also uninstalled AIDA64 - I am convinced it's not near as good as Prime95, but even when Prime95 was stable, I still had WHEA errors @ 1.265 V @ 4.4ghz - but my temperatures were getting to high so I backed down to 1.240V @ 4.3GHZ
I don't think I got the best chip, whereas my invisible "voltage wall" was at 4.4GHZ, many people get that same problem @ 4.5 GHZ from my reading.