Z87-Plus Firmware
While Asus spent a lot of time on its user-configurable UEFI start page, the most interesting settings are still found in the firmware’s Advanced menus. The company prepared a video walk-through that outlines its efforts.
The Asus Ai Tweaker menu offers separate manual and XMP modes, which are virtually identical, except that XMP overclocking mode starts with an XMP-based memory overclock. You can still change memory multiplier and timings, even after enabling an XMP profile.
The Z87-Plus eagerly pushed our CPU to 4.7 GHz at 1.3 V, though we recently discovered that tests heavily optimized for AVX cause thermal throttling at that voltage. Dropping to 1.25 V, the processor was stable at 4.6 GHz.
Because Intel's fourth-gen Core processors don't support 30 x 100 MHz memory ratios, the Z87-Plus configures our XMP-3000 profile using an increased base clock rate paired with a DDR3-2933 ratio (22 x 133 MHz). We eventually topped the memory’s maximum data rate at 1.65 V by reaching DDR3-3021. In the words of Jim Carrey in The Mask, smokin'!
The Z87-Plus adds slightly more than 25 mV to whatever memory voltage setting you specify, so we dropped to 1.625 V. Our meter showed between 1.651 to 1.654 volts after making that change.
Primary, secondary, and tertiary timings can be individually switched between automatic and manual configuration. We lock in our memory’s primary timings during overclocking tests.
The Haswell architecture's fully integrated voltage regulator makes it impossible to apply traditional CPU load-line calibration. Asus compensates somewhat by adjusting VCCIN. We achieved stability there by choosing the board’s "Level 2" Load-line Calibration setting.
Other overclocking options include Auto OC By Ratio and Auto OC By BCLK. The first method raised our CPU multipliers to 41-42-43-43x (4.1 to 4.3 GHz, depending on utilization) at stock voltage, and picked a data rate of DDR3-2400 at 1.65 V. The second method used a fixed CPU multiplier of 34x and a DRAM multiplier of 20x, with a 125 MHz base clock pushing the CPU core to 4.25 MHz at stock-voltage and DRAM to DDR3-2500 at 1.65 V.
