DIGI+ Power Control:

Each of the settings within the DIGI+ VRM section has an explanation listed in the right hand column of UEFI. All settings have been configured to scale on Auto in accordance with overclocking. We recommend you leave the thermal control parameters as is for all operating conditions. We’ll highlight some of the other settings below for clarification purposes.

Load-Line Calibration:

AKA LLC, sets the margin between applied and load voltage. For 24/7 use a setting of 50% is considered optimal, providing the best balance between set and load voltage in a manner that compliments the VRM for all loading conditions. Some users prefer using higher values, although this will impact overshoot to a small degree.

VRM Spread Spectrum:

ssigns enhanced modulation of the VRM output in order the peak magnitude of radiated noise into nearby circuitry. This setting should only be used at stock operating frequency, as the modulation routines can impact transient response.

All “Current Capability”settings:

A setting of 100% on all of these settings should be ample to overclock processors using conventional cooling methods. If pushing processors using LN2 or other sub-zero forms of cooling then increase the current threshold to each voltage rail respectively. A setting of 140% should ensure OCP does not trip during benchmarks.

CPU Voltage:

There are two ways to control CPU core voltage; Offset Mode and Manual Mode. Manual mode assigns a static level of voltage for the processor. Offset Mode allows the processor to request voltage according to loading conditions and operating frequency. Offset mode is preferred for 24/7 systems as it allows the processor to lower its voltage during idle conditions, thus saving a small amount of power and reducing unnecessary heat.

The caveat of Offset Mode is that the full load voltage the processor will request under load is impossible to predict without loading the processor fully. The base level of voltage used will increase in accordance with the CPU multiplier ratio. It is therefore best to start with a low multiplier ratio and work upwards in 1X steps while checking for stability at each increase. Enter the OS, load the CPU and check CPU-Z to check the voltage the CPU requests from the buck controller. If the level of voltage requested is very high, then you can reduce the full load voltage by applying a negative offset in UEFI. For example, if our full load voltage at 45X CPU multiplier ratios happened to be 1.40V, we could reduce that to 1.35V by applying a 0.05V negative offset in UEFI.

Most of the information pertaining to overclocking Sandy Bridge CPUs has already been well documented on the internet. For those of you purchasing retail Ivy Bridge CPUs, we expect most samples to achieve 4.3-4.5GHz with air and water cooling. Higher overclocks are possible although full-loading of the CPUs will result in very high temperatures even though the current consumed by these processors is not excessive. We suspect this is a facet of the 22nm process.

iGPU Voltage:

Sets the rail voltage of the integrated GPU. Same function as CPU Vcore with regards to Manual and Offset Mode. Should this option become available when you are not using the iGPU, then you may force the iGPU to disabled via System agent config > graphics config/ option > internal graphics. Doing so ensures better memory stability and overclocking headroom.

DRAM Voltage:

Sets voltage for the memory modules. 1.50V DIMMs qualified on Sandybridge and Ivy Bridge processors are recommended for use on this platform.

IMC-DRAM Offset Sign:

Selects whether or not to add or subtract voltage from the IMC-DRAM Offset function below.

IMC-DRAM Offset:

This setting offsets the DRAM voltage seen by a portion of the memory controller. The based voltage at AUTO is DRAM voltage. By using the positive or negative setting above, we can offset processor side DRAM voltage in 0.00661V steps. The reason this setting has been added is we found that some DIMMs exhibit more stability when a specific processor side DRAM pin has its voltage set above or below the voltage supplied to the memory modules. Usually a setting 5 steps above or below DRAM voltage (circa 0.02V) is sufficient to help in memory intensive benchmarks. In my testing to date the memory ICs that seem to respond best to an offset are Elpida BBSE based modules. Don’t stay too far from auto.