The Core i7-980X might be labeled as a 3.33 GHz model, but Intel's Turbo Boost technology automatically increases its clock rate to either 3.60 GHz or 3.47 GHz, depending on the number of cores being used. The screen shot below doesn’t show exactly 3,466 MHz because Gigabyte doesn’t set its base clock to a proper 133.33 MHz. With a default base clock of around 135 MHz, choosing manual settings to reach Intel’s intended 133.333 MHz base clock results in an actual clock speed of 133.0 MHz.
Notice that the highest temperature reached by our CPU at stock settings was measurable, exceeding the lowest-possible reading of its DTS (digital thermal sensor) at -12° Celsius. While we couldn’t track temperatures this cold in real time, the fact that they occasionally exceeded the minimum threshold tells us that the CPU core is much warmer than the -50° evaporator temperature reported by the Cooler Express status monitor.
I dropped my personal test voltage limit for Intel's 32 nm technology to 1.35V after a rash of blown processors swept Tom’s Hardware labs at settings as low as 1.375V. But those articles used air cooling, and processors do gain some voltage tolerance as temperatures are lowered. Today we use my air-cooled 1.35V limit as the starting point for our chilled-overclocking effort.
A modest 1.35V is already pushing our CPU temperature into positive numbers at full load, and we’re beginning to wonder whether surface imperfections on the evaporator will need to be addressed if we’re to maintain useful temperatures going forward. The CPU is coping admirably, reaching 4.46 GHz at 100% stability.
Our next step is 1.45 volts, which yields a stable 4.69 GHz at full load with Intel Hyper-Threading turning our six physical cores into twelve logical cores. Temperatures are still acceptable, climbing only a few degrees from our 1.35V results. Normal caution would have us stop here, but we’re committed to finding this processor’s limit or reaching 5 GHz, whichever comes first.