With each new CPU generation, the expectations of the enthusiast community gets higher. While with I7 s1366 4.5Ghz was doable for some. Not everybody reached them clocks for daily use ( this with Hyperthreading on)

The early non NDA results showed in some benchmarks clocks of 5ghz and beyond on air for the Sandy Bridge CPUs. Some tests were even executed on the boxed cooler (with a little help form cool ambient or a portable AC unit).

Time to explore what can be done on a Thermalright Venomous X with one 120mm fan running at 1600rpm.

For testing I ran a two different scenarios :

First test with stock volts (my 2 CPUs were both detected set at 1.2 Vcore by the Asus bios) and the P8P67 DLx equipped with the Thermalright Venomous X

Not bad at all : 4.2ghz for the 2500K and 4100Mhz for the 2600K. OC potential will depend a lot on ya CPU binning, motherboards power circuitry and co.So don't shoot me if your CPU might not reach the above clocks. if yours do better I'm in for a trade :)

How about 4.5Ghz maybe for daily clocks ? After some fiddling around in the bios both CPU's required about +/- 1.3Vcore to maintain prime stability. Main key on my setup is to keep the CPU voltage stable via the motherboard loadline calibration settings. Here's a screenshot of my bios settings for the P8P67 Dlx (latest bios 1253) :

This setting allows me an OC of 4.5Ghz ( so with reasonable volts and temps ) and yet the CPU steps down when being unused or light loads to eg 1600mhz at 1.0 Vcore. Ofcourse these settings can differ from board to board and CPU. The same CPU is benchable at 1.485Vcore at 5200mhz with just a few alterations in the bios.

Now why not push for higher ? Well take a look at the below charts for the temperatures with my VenomousX and a single fan spinning at 1600rpm :

I'm not the type of guy that likes high temps and if an hour prime95 ( Custom test 12K ), can cause this heat output. Then you think LinX or another Intel Burn test program can do even worse. Well lads, it's the inverse world now. With the 2600K, Prime95 version 36 is more stressful then the latest LinX version. For proper Intel Burn test stress testing Windows7 has to be updated with Service pack 1 ( it's required to use AVX instructions ) In real applications your CPU will never ever get this hot. But I'm aware that some will push for a 100 - 200 LinX run or a 24 hour Prime test. Till now, we got no idea if CPUs will degrade  with high Vcore under air or exotic cooling. Only time will tell.

There's already one death reported,  but that owner pushed 1.72Vcore through the CPU, just for a CPU-Z validation screenshot. Think he's the cause of his loss, yet he screams for RMA as he isn't happy...
It isn't because someones CPU can do 5ghz , that yours can do too on the same setup. We tested a few CPUs at the Tones Sandy Brunch event. Out of 5 ( all same batch) when benching there was already a discrepancy  of 300Mhz. Hwbot is starting a batch thread right here

A golden rule : Take it slow, monitor temps, there's more than enough OC potential in these beauties.

And then some fun screenshots, these can be obtained after just 15 mins of tweaking: this platform rocks !! 

More overclocking results by Massman on the next page