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ASUS ROG Maximus V Formula UEFI OC Tuning Guide
This guide covers UEFI OC tuning for ASUS the Maximus V Formula motherboard. Most of the available UEFI options are similar to other motherboards from the ASUS Z77 family, with the exception of extra voltage controls and memory profiles – both of which provide extra overclocking margin and ease-of-use. We cover most of the available functions below, and provide a brief description of what each does and when to adjust (where applicable).
All of the overclocking related action takes place within the AI Tweaker Menu (UEFI Advanced Mode):
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AI Tweaker Menu with AI Overclock Tuner set to Manual
Load Gamer’ OC profile: This will load a preconfigured overclock suitable for a 24/7 system with adequate cooling.
Load Ivy Bridge LN2 Extreme OC Profile 1 & 2: These options are available when the onboard LN2 jumper is set to enabled. Both presets are for use with Ln2 cooling only as the voltages and settings used require the processor be sub-zero cooled for both safety and stability purposes. Do not use these settings with air or watercooled processors.
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). Whil Ivy Bridge CPUs are binned to run a maximum of DDR3-1600. Higher operating frequencies are defined as overclocked, so voltage requirements and overall stability will vary from CPU to CPU.
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. At subzero processor frequencies, most processors need BCLK to be set at ~ 105MHz to POST. Some sample need upwards of 110 MHz when cooled to temperatures lower than -120 Celsius.
We’ve included an auto frequency calculator which displays the target CPU and memory bus frequency for you in the top left area of the AI Tweaker menu:
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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.
Internal PLL Overvoltage: Increases internal phase locked loop rail voltage, allowing higher processor core frequency overclocking. A setting of Auto will enable this setting for you as you increase the CPU core multiplier over a certain threshold.
Most good processor samples will not need this setting enabled until overclocking past a core multiplier of 45X (4.5GHz CPU speed).
The stability of S3 sleep resume may be affected with this setting “Enabled”. If you find that your CPU won’t overclock past 4.5GHz without this setting Enabled, then the only choice may be to run at a lower speed if you find the system is unable to resume from S3 successfully.
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CPU bus speed DRAM speed ratio mode: This setting is for Ivy Bridge processors only. Can be left at Auto to apply changes in accordance with the Memory Frequency setting.
Memory Frequency: Selects the desired memory operating frequency (memory ratio). This setting is a derivative of BCLK and CPU bus speed DRAM speed ratio mode. The target operating frequency is displayed within the drop-down list of this setting as well as the top-left corner of the Ai Tweaker menu.
Ivy Bridge CPUs have a wider range of memory ratio settings at their disposal than the previous generation Sandybridge processors. When used in addition with BCLK*, this allows more granular bus frequency control which should help us to tune a system to its full potential.
For daily use, we recommend opting for memory kits specified at a maximum of DDR3-1600. This is the highest default speed supported by Intel at stock processor voltages. That means that the processors have been binned by Intel to achieve this frequency without requiring voltage adjustments.
Higher speed memory shows miniscule performance gains in most desktop software, so it is wiser to spend money elsewhere on the system. Further, the stability of the system at higher operating frequencies cannot be guaranteed, possibly interfering with resume from sleep states and also when the system is stressed by software unless tuned manually. Hence our advice to opt for memory kits that are within processor specifications if you prefer plug-and-play operation.
At the other end of the spectrum, benchmarking fanatics will find that 2GB PSC and Elpida BBSE based kits offer the best overall performance in memory sensitive benchmarks. Target operating frequencies between DDR3-2400 to DDR3-2600 seem to be the optimal point for best scores and times in sensitive benchmarks utilizing CAS 6 or 7 timing sets, in tandem with sub-zero cooling of both the processor and memory modules. Higher speeds are possible at the expense of secondary and third memory timing parameters, although latency will suffer unless operating frequency is increased substantially. If PSC or BBSE based kits are not available, then Samsung based kits offer a modern alternative albeit requiring looser operating latency at equivalent frequencies.
*Within functional limits of the BCLK setting.