ASUS Z77 Motherboard UEFI BIOS Tuning Guide

This guide covers UEFI tuning for ASUS Z77 motherboards, including P8Z77 series, Sabertooth Z77 and Republic of Gamers Maximus V series. For the most part, the default auto settings for each parameter should suffice – we’ve selected optimum parameters for some of the more complex settings in order to allow users to achieve a successful overclock without too much fuss. If you are curious as to what some of settings do, or how/when they should be used, then you will find this guide of some use.

All of the overclocking related action takes place within the AI Tweaker Menu (UEFI Advanced Mode)

AI Tweaker Menu with AI Overclock Tuner should be set to Manual for full control.

Ai Overclock Tuner:

Options are Auto, Manual and X.M.P.

Auto: This is the default setting, and needs to be changed to Manual if you wish to change BCLK (BCLK is the base reference frequency from which processor and other system bus frequencies are derived).

X.M.P:

Extreme memory profile, use this option if you have Sandy Bridge/Ivy Bridge qualified XMP memory.

X.M.P. profiles contain pre-sets for system buses and in some cases voltages. If the specified speed of the DIMMs is greater than the supported memory frequency of the platform, a platform specific X.M.P. profile option becomes mandatory because processor core and memory controller voltage requirements vary from architecture to architecture.

High-speed enthusiast memory kits manufactured before the inception of the Sandybridge/Ivy Bridge platforms may not contain the necessary/adequate voltage offset settings for the system to be completely stable. In such instances, manual adjustments of memory controller voltage and memory timings may be necessary.

It is also wise to purchase a single memory kit rated at the density and timings you wish to run rather than combining multiple kits to make up that density. The XMP profile and memory module SPD is configured by the memory vendor for a single kit only and does not take into account timing and voltage offsets that may be required for two or more kits to operate in tandem. One of the reasons that high frequency high density kits are more expensive than their lower density counterparts (even when the operating frequency and IC used is the same) is because the binning process at higher densities is more stringent – only a few ICs make the grade. Making a wise investment here will save frustration later on.

A final note on memory purchasing; Sandybridge processors are binned to run DDR3-1333 speeds at stock voltages (CAS 9). Higher operating frequencies are defined as overclocked, so voltage requirements and overall stability will vary from CPU to CPU. The same rule applies to Ivy Bridge processors, although the margin has been extended to DDR3-1600 at stock voltages for these CPUs. As such, unconditional stability at higher operating frequencies cannot be guaranteed and will vary between processor samples.

BCLK Frequency:

This function becomes available if X.M.P or Ai Overclock Tuner “Manual” are selected. The base BCLK frequency is 100MHz. The CPU core frequency is derived via multiplication with the Turbo Ratio setting (final frequency is displayed at the top-left of the Ai Tweaker menu). BCLK also adjusts memory operating frequency in association with the applied memory ratio (Memory Frequency and CPU bus speed: DRAM speed ratio mode settings below).

Bear in mind that the adjustment margin for this setting is not large – most processors have a range of 7 MHz +/- the base frequency, although there are some processor samples that can exceed this.

To make things easier, we’ve included an auto calculator which displays the target CPU and memory bus frequency for you in the top left area of the AI Tweaker menu:

ASUS MultiCore Enhancement:

When enabled sets ASUS defined Turbo core ramping policies. Disabled will apply Intel Turbo core ramping policies. For all overclocked configurations a setting of Enabled is recommended. Disabled can be used if you wish to run the processor within Intel guidelines when non-overclocked.

Turbo Ratio:

Options are “Auto”, “By All Cores” and “By Per Core”. A description of these settings is provided in the right-hand column of the UEFI BIOS and can be seen when the Turbo Ratio setting is selected.

By All Cores: This sets the CPU core frequency multiplier; multiplied by BCLK to give the target CPU frequency (under full load conditions if SpeedStep is active). “Auto” = stock CPU multiplier Ratio used. Manual numerical entry of the desired Turbo Ratio is accepted. *

Per Core: Allows setting the maximum Turbo multiplier of each physical processor core.*

*The available multiplier range is limited by both processor model and the ability of each CPU.