Overclocking with the H57H-MUS and Clarkdale

Overclocking with a Clarkdale processor

Ever since we met the Nehalem family of processors the Front Side Bus was officially annihilated, things tend to change a little in the overclocking department. Only a little though. It's a little weird but the concept remains the same. In the BIOS you'll find a 133 MHz register, labeled the base clock -- look at that as your 'FSB' to play around with. Of course, if you have an Extreme Edition processor, things would be much easier as they have unlocked multipliers; unfortunately this is not the case with the processor we use today.

The processor we used today is multiplier locked, meaning you select the highest possible multiplier and then increase the base clock in the BIOS or Windows tweaking software that comes along with your motherboard.

Just play around with CPU voltage and even on the stock air cooler you can achieve some pretty snazzy results. So we were able to overclock the Core i5 661 processor to 4 GHz on an air cooler (!). Here's what we did:

• Set maximum processor multiplier (25 for the 660/661 on the ECS H57H-MUS)
• Increase processor voltage to 1.35v
• Increase CPU base frequency (we ended up at 160 MHz)
• Set QPI ratio as close as possible to 6400
• Lower memory multiplier to maximum stable memory frequency at maximum memory frequency
• At 4 GHz on the air cooler we easily boot into Windows. We settled at 25x160 @ 1.35 Volts

When we stress the CPU cores with Prime 95, temperatures now rose to only 55 degrees C (131F) which was way under the maximum limit. Very nice.

Overclocking itself, it is a pretty easy thing to achieve with this processor. The system remained 100% stable at 1.35 Volts / 4.0 GHz at roughly 55 degrees C on the processor max (room temperature is 21 degrees C). We undoubtedly could have taken it a little further if we wanted to.

Overclocking and power consumption

Okay, check this out then:

What a lot of you do not realize is that overclocking a processor will consume more power. We put this to the test by monitoring power consumption with the processor at its default settings and then overclocked to 4 GHz.

When we stress the 2 (4 threads) CPU cores 100% at default (non-overclocked) we peak at roughly 108 Watts (with a dedicated R5870 graphics card installed). Once we overclock to 4 GHz the power consumption all of a sudden is 160'ish Watts and thus is costing us an additional 50 Watts.

Definitely something to think about before you start to overclock, but by far not as bad as overclocking the quad-cores TBH. Temps wise, things stay very manageable with a decent heatpipe based cooler.