For our overclocking tests we push the FSB/reference clock as high as possible, but please bear in mind that the actual CPU used may hinder the overclock of the motherboard.
To do this we lower our 965 EE CPU's multiplier to its minimum (x12), set the memory speed to the lowest available divider (x3), and increase the appropriate voltages to 10 per cent over reference levels, or as close as we can get with the BIOS options available without going over.
We test for stability using four instances of Prime95, incrementally increasing the FSB/reference clock between runs until failure. We then back the FSB back down until we find the maximum stable limit.
With overclocking, your results may vary from ours, of course.
Some examples of a board are liable to overclock to a greater extent than others, and as such the figures given should be taken as a rough guide rather than a definitive or guaranteed limit.
As the motherboard doesn't allow you to normally set the multiplier any higher than the default, we had to enable and use Intel Turbo Boost tech, to increase the CPU multiplier when trying to overclock the CPU. In order to ensure it didn't throttle down under-load when using a multiplier greater than 26, the TDP and power consumption limits of the CPU had to be overridden and set to 300W and 300A, respectively.
Instead of using the onboard dip-switches which are quite
awkward to access when three dual-slot GPUs are installed, the CPU
reference clock was adjusted in the BIOS. Using our normal method as
outlined above, we were able to achieve a maximum reference clock of
200MHz (3.6GHz QPI). Moving onto the CPU, we managed to coax
it to a reasonable, stable clock speed of 3.87GHz, but the CPU was able
to complete POST and boot into Windows Vista at 4GHz, Here, though, it
would crash during running Prime95 after less than two minutes.