We chose Gigabyte's Z77X-D3H based on our own recommendations. And yet, we suggested the Gigabyte board for enthusiasts on a more limited budget. We had apparently forgotten why the company's -D3H-series motherboards had previously been left out of our high-end builds since last year, only to remind ourselves on overclocking day.
We wanted a constant voltage level between 1.25 and 1.30 V. But the Z77X-D3H's voltage regulator simply couldn’t do what we asked under the rigors of overclocking. Setting the firmware’s Loadline Calibration setting to High kept the voltage where we wanted for a while. But, again, full-load testing stress caused a protection circuit to reset the system. The same safeguard keeping us from destroying the board instead inhibited our overclock, even though the processor was never active for long enough during real-world testing to exceed 70° Celcius.
The Medium Loadline Calibration setting allowed the core to drop to around 1.23 V under full load, in turn limiting our processor's maximum clock to 4.4 GHz.
The issues didn’t end there however, as the Core i7-3770K eventually climbed to 84° Celcius, even at our more conservative settings. Had we picked a motherboard better able to contend with aggressive overclocking, the mediocre heat sink and fan would have been our next bottleneck to address.
A combination of overclocking consistency and value pricing put G.Skill's 8 GB DDR3-1600 kit in our system. Proof of that consistency came when it achieved the same DDR3-2133 data rate at 10-11-10-24 timing seen in our previous $2,000 build.
Graphics cards tend not to be as flexible as host processors when it comes to voltage levels and overclocked frequencies, but we didn't need any more voltage to push the limits of MSI’s Radeon HD 7970 cards.
Automatic fan speed wasn’t sufficient for our overclocked settings, though. So, we set a simple slope in MSI Afterburner’s advanced settings. We also set “Start With Windows” and “Start Minimized” under the program’s General tab.