Overclocking
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Since the Core i7-3960X is an unlocked CPU, we have several adjustments available, including the adjustment of the clock multiplier for each core and the TDP and current limits of the CPU.
The “correct” way of overclocking Intel CPUs with Turbo Boost technology is to change the clock multiplier that each core will use when the Turbo Boost technology kicks in. This can be done on the motherboard setup or using the Intel Extreme Tuning Utility, which has a handy stress test to see if the system is stable.
We could put the Core i7-3960X to work with its six cores at 4.3 GHz at the same time by increasing the clock multiplier of all six cores from 33x to 43x, after increasing the CPU voltages (see Figure 7) and the current limit from 135 A to 165 A. We were afraid of increasing the current limit even further and burning our CPU, so if you have nerves of steel you may achieve an even better result.
Figure 7: Six cores working at 4.3 GHz
Then, we decided to reduce the number of active cores. This way, the total thermal dissipation is decreased and, because of that, we were able to increase the clock rate of the active cores. We disabled two cores for a total of four active cores and were able to increase the clock multiplier for these cores to x45, making them work at 4.5 GHz. We used the same voltages and current limit as before.
Figure 8: Four cores working at 4.5 GHz
Even on locked CPUs, you can increase the CPU base clock; however, second-generation Core i processors have very tight overclocking limits for this clock. The system crashed whenever we tried to increase the CPU base clock during the tests described above.
Once again, we were afraid of burning the CPU and probably didn’t reach all the overclocking potential of this CPU.
