The ROG team have put an extensive amount of work into UEFI for the R4E. Most of the settings will not need manual adjustment at all unless you are chasing every last MHz from your system. This guide will focus on the meaning of most of the important settings and offer some insight as to when adjustments can help. We will follow up with a quick setup guide for beginners also.
Upon entering UEFI BIOS, we navigate to the AI Tweaker menu:
Load Normal/Gamers/Extreme OC Profile: Each of these settings contains a pre-set that sets system bus frequencies and voltages for a quick starting point if you’re new to overclocking. The Normal profile will overclock your CPU to 4.375 GHz, the Gamer profile to 4.7 GHz. The Extreme profiles are for users that are utilizing Sub-zero cooling or chilled watercooling as both will set processor frequency at around 4.9GHz. With all of these profiles, active cooling of the onboard heatsinks is required.
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 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 platform 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.
Selecting the X.M.P setting opens up options for X.M.P profile selection (the kit may contain more than one X.M.P profile), and also opens up the BCLK option for changing system bus frequency. Note that memory operating frequency and maximum CPU operating frequency are shown towards the top of the Ai Tweaker menu, while memory timings and voltage are displayed next to the XMP profile selection box.
CPU Level Up: Allows us to select a pre-set profile that contains voltage and bus adjustments to apply a mild overclock to the system. Use this setting if you do not wish to overclock the system manually.
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).
Bear in mind that the adjustment margin for this setting is not large - most processors have a range of 7 MHz +/- the base frequency. For example, if using a CPU Strap setting of 100MHz, then the approximate maximum BCLK for some CPUs is 107.0 MHz. If using the 125 MHz strap, then we’d expect a maximum in the 130 BCLK range.
CPU Strap: This setting multiplies BCLK to increase CPU frequency asynchronously from all other bus frequencies giving us more granularity to maximise processor and memory overclocking. Available settings are 100, 125, 166 and 250 MHz. For most CPUs the usable “straps” are 100 and 125 only. If using 166, try starting at 155 and see if the board will POST. If not, then you are likely limited to using 100 and 125 only.
Clockgen Full Reset: Re-initializes the on-board clock generator when bus frequencies or multipliers are changed. A setting of Enabled is recommended for all normal syste use. Disable only to experiment with memory stability when making changes to BCLK.
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. Note that if overclocking past 4.5GHz, it can be beneficial to turn disable the Anti Surge Support setting in the Monitor section of UEFI to prevent power shut-off due to Super IO polling.
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.