Sabertooth Z77 Firmware
Asus' AI Tweaker menu hasn’t changed much in the past few years, providing both fully-manual and XMP-based manual overclocking capabilities. The difference between those two options is that XMP starts the process with higher DRAM timings, voltage levels, and data rates.
Our combination of XMP and power controls also locked out CPU ratio selection from the main menu, though synchronized ratios can still be selected from the CPU Power Control submenu.
A 1.245 V CPU core setting got us an actual 1.25 V, providing CPU overclocking stability up to 4.67 GHz.
Manufacturers have been quietly pushing higher DRAM voltage, apparently in an effort to boost DRAM overclocking, but that really wasn’t necessary for the Sabertooth Z77. A 1.625 V setting produced 1.65 V at the DIMM slot in spite of the false 1.630 V firmware reading, and the board was able to push G.Skill’s DDR3-2666 to DDR3-2800 in spite of our compensation efforts.
Primary, secondary, and tertiary timings are all accessible for memory tuning.
Depending on other settings, the CPU ratio may be accessible only from the CPU Power Management submenu. Asus also provides over-current protection adjustments here, but told us that Auto is the best choice for all but the most extreme (high-voltage) overclocks.
The Sabertooth Z77’s Ultra High Load-Line Calibration setting is supposed to reduce voltage droop by 75%, but it actually caused our voltage to go up by a few millivolts at full load. The effectiveness of each load-line level varies with changes in baseline core voltage and overclock amount.