Overclocking with Sandy Bridge processors

Overclocking with Sandy Bridge processors

We've mentioned at the start of this article already, if you are planning to do some overclocking with a Sandy Bridge based processor, you are so much better off with a K model processor.

Why K versions you ask? Well, the default Sandy Bridge processors will be much harder to overclock. With Nehalem/Clarkdale (last generation Core i3/i5/i7) pretty much you take your base clock of 133 MHz and apply say a default multiplier of 25, that would be your 3.33 GHz processor. That base clock was capable of going so much higher, 150, 186 and when tweaked right, even over 200 MHz. So if you were able to apply a fictive 175 MHz on your base clock, you could multiply it with the limited 25 multiplier. That would get you 4375 MHz.

The new technology however has an embedded GPU / video processor merged into the very same processor die running over the same bus sharing the same L3 cache memory, things get increasingly complicated in matters of tweaking.

The new 100 MHz baseclock of Sandy Bridge processors is hard to tweak, if you are lucky you can get 115 MHz out of it with regular cooling, multiply that with your maximum multiplier and you'll notice that the default 2400/2500/2600 processor can only overclock a few hundred MHz at best. And that is why Intel introduced the K series, since it offers you an unlocked multiplier which will allow you to go much, much higher.

So get yourself a 20 USD more expensive K version and in the BIOS you'll have much better tweaking options. With a proper motherboard you can now set a multiplier per core.

The generic overclock procedure is as follows:

1. Leave baseclock for what it is right now
2. If optional in the BIOS, increase your TDP limits of the processor to 200 Watts (by that you are allowing a higher power draw).
3. With a 2600K set your base multiplier at 34
4. And now set the per core multiplier at a maximum of your liking, we applied an MP of 48 on all four cores
5. Increase CPU voltage, though setting AUTO might work fine, we applied 1.36V on the processor core
6. Make sure your processor is properly cooled (we used the stock Intel cooler and forced the fan to 100% RPM)
7. Save and Exit BIOS / EFI

So these settings allow us to work at a baseline clock of roughly 3400 MHZ that actually still can throttle down to 1600/1800MHz in idle, which helps us in power consumption. However, once the processor gets a kick in the proverbial nuts, it can turbo any or all cores towards that multiplier of 48 times that 100 MHz baseclock frequency, that's a 4800 MHz configuration.

Let's have a look at a Prime95 stress test with all four cores active and stressed at ~4800 MHz...

Now we used stock Intel cooling here ... but we did apply a noisy 100% fan RPM, still it's an average cooler at best and this was for demonstration purposes only. Overclocking wise could likely take it even further here, that baseclock frequency would work at ~105 MHz as well, multiply that with say an MP of 48 and that gets you at 5+ GHz.

Our overclock towards 4800 MHz was very stable, and will be integrated into the test sessions. On top of that we flicked on 2133 MHz for the DDR3 memory from GSKILL. The memory bandwidth you're about to see is Jawbreaking alright.

So all benchmarks will have these overclocked results embedded into our article. The K editions kick ass and absolutely will offer the most bang for buck, to the enthusiast crowd of course.