The results below are based on the range of the CPU turbo multiplier when overclocking (sole multiplier).
Results are representative of 100 C0 and 20 C1 CPUs that were binned and tested for stability under load; these results will most likely represent retail CPUs. BE ADVISED CPU vid varies considerably for the same frequency between CPUs as always cooling also will affect CPU frequency scaling.
- Approximately 90-100% of CPUs can go up to 4.5GHz
- Approximately 80-90% of CPUs can go up to 4.6GHz
- Approximately 60-70% of CPUs can go up to 4.7GHz
- Approximately 40-50% of CPUs can go up to 4.8GHz
- The remaining % can yield CPUs that may offer scaling up to and in excess of 50x turbo multipliers. These CPUs are in very low % margins and in addition voltage required will considerably vary (i.e 4.8GHz at 1.400 vs 4.8GHz at 1.500). In most situations due to the excessive wattage level that needs to be dissipated unless a extremely non leaky chip (low voltage operation is hard) frequencies exceeding 5.0GHz will not be achievable under air cooling configurations.
IMC (Integrated Memory Controller)
The results for IMC (memory divider frequency scaling) varies considerably. Most CPUs will hold 1600 in full 8 DIMM without issue although considerations for adjusted subtiming and VCCSA and VTT voltages will need to be considered as variance will come into play. It is
important to keep in mind profile specifications such as XMP are defined for broad / worst case CPUs as well as lower quality boards as such values defined may be inefficient (and in some cases overtly aggressive causes stability issues).
In addition for long term CPU lifespan and reduction of draw and heat considerations VCCSA and VTT value of 1.100 are advised. When exceeding 1600 speeds 1.150 to 1.200 may be required for 1866+ it is strongly advised you attempt lower operating voltage levels first and if all possible maintain 1.100 as your maximum. Considerations for defining and maintain a 1.200 can be considered but are still under analysis currently ASUS has reached frequencies in excess of 2800 in full 8 DIMM population when the quality of the IMC is high. Highest DRAM scaling has been achieved with 1.300 to 1.400 with currently no signs of issues until more analysis is completed though it is still only advised to use up to a maximum of 1.200v with an ideal recommendation for 1.100.
(In most situations most IMCs will not have an issue scaling up to 2133 in at least 4 DIMMs) when considering 8 DIMMs please consider validated minimum closer to 1600.
Some items to reference regarding how to bin/range your IMC are detailed below.
Reference the Debug code on the motherboard during attempted DRAM overclocking session. This will help you to reference that area of failure and how it may affect yoru DRAM scaling process.
When attempting the overclock if the debug code read/display passes B1 and goes into 00/B3/B4 that indicates that the CPU’s IMC is not capable of the frequency you are attempting to reach. If it is related to timings you are more likely to see a display of B7 and after that a debug report / crash or stop error which could be in displayed as 01/32 or a general shutdown of the system.
Outlined Debug readout and explanations
00 after B1 – The IMC is not capable of this divider/frequency
B3 or B4 – The IMC is reaching its limit , attempt scale down and reduce frequency
Assuming scaling/post and booting go correctly and you scale in increments of 1MHz you will see B3 or B4 and then 00
Board variance and how it affects CPU scaling.
What does going higher in the board stack provide overclocking wise?
ASUS’ entire line of X79 motherboards features a class leading and high performance Digi+ VRM with Digital Power Control this implementation allows for superior overclocking performance and extensive VRM control when matched with our advanced and tuned UEFI it will offer the most robust OC experience on the X79 platform; When considering a board and how it may affect your OC experience we have gone to great lengths to implement a consistent high performance design that will allow for the limitation to be more dependent on the CPU than the board. In addition all of our boards feature new advanced MOSFET and Driver package designs with high rated chokes. Keeping this in mind as you go up in the segmentation more advanced heatsink assemblies help to extend and maintain OC headroom due to superior VRM operating temperature. Boards such as WS, SABERTOOTH, Deluxe have very robust VRM cooling implementations so at higher load and frequencies you should be able to maintain superior stability. For ROG this board does stand apart as not only on a power delivery implementation but UEFI implementation will provide the most control and tweakbility with advanced control and superior power delivery than any other ASUS board or any other board on the market.
To recap while our entire board lineup has been internally tested to fully support both X and K series processors and provide and maintain high level overclocking performance, when overclocking in multiplier ranges of 48x and higher our higher end boards will benefit in two key categories.
- Better Vdroop efficiency. This is partially due to advanced heatsink cooling providing superior VRM efficiency this is especially true on Deluxe and WS and more so on boards with active VRM cooling SABERTOOTH X79 and Rampage IV Extreme.
- The ability to help drive and sustain a 50+ high load Overclock under maximum loads. Examples of boards that focus on this level are our Deluxe, WS, SABERTOOTH, and Rampage IV Extreme
- More advanced VRM designs (higher rated components and specialized onboard component choices as well as custom tuned UEFI options.
For reference on consistent overclocking experience please see attached screenshots of all motherboards overclocked to 4.8GHz with DDR31600C9 (32GB) running under latest Aida64 Stability Test suite along with simultaneously running Unigine (all boards were run at those speeds and stress values for a minimum of 1 hour).