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Skylake-X Overclocking Guide

By: Steven Bassiri | Socket LGA 1150/1151 in Motherboards | Posted: Feb 27, 2018 12:00 am

CPU Multipliers



We are including all brands in this guide because vendors tend to rename Intel's settings to their own brand's typical naming scheme.



Multi-core Enhancement is a feature that will take all CPU cores to maximum Turbo frequency, which is out of Intel's specifications, but it's an easy overclock. However, some vendors have built-in overclocking profiles. We tend to avoid them, but if you like, you can apply them and see what settings they change.




We are going to bunch all the CPU ratios together. For starters, you can do a per core overclock, where you overclock each core to a different level, but we prefer putting all cores to the same level. On some brands, you get more types of overclocking modes, such as ASUS allowing you to set XMP, which then enables all cores to maximum Turbo ratio. All Core Ratio, CPU Core Ratio, CPU Clock Ratio, and CPU Ratio are all the same setting; your CPU's multiplier. The Flex Ratio is the minimum ratio the CPU will sit at when idle.



The platform also allows you to change the BCLK for the CPU and memory separately from the system's BCLK in case you want to overclock with it, but we recommend sticking with ratio/multiplier overclocking. CPU Mesh Max OC Ratio, Max CPU Cache Ratio, CLR (Mesh) Ratio, and Ring Ratio are all the same thing; they control the speed of the mesh/cache. You should OC the CPU first and then the mesh, as the CPU core frequency has a more profound effect.




AVX uses parts of the CPU typically not used and as such will greatly increase power consumption, temperatures, and it could require more voltage to remain stable. Intel has added in an AVX Offset setting, which allows you to set a number of multipliers for the CPU core to drop down to if AVX is engaged. The new Skylake-X CPUs feature not only AVX-2 but also introduced AVX-512 (AVX-3). The setting is important if you are crashing because of AVX workloads.




The CPU now has two voltages because Skylake-X brings back the Integrated Voltage Regulator. You get a CPU Input Voltage, by default this is 1.8v, but you should definitely increase this voltage. If you don't, you will be bottlenecking performance. I would set 2.0 or 2.1v for the Input Voltage. CPU Input Voltage is also called CPU VRIN External Override or VCCIN Voltage. CPU VCore is the voltage to the cores and derived from the internal voltage regulator. I would stay under 1.3v for LCC CPUs and 1.2v for HCC CPUs. In the case of VCore, you will be limited by your cooling, so you won't be able to get away with 1.4v unless you have a delidded CPU or really good cooling.


You also can use offset, adaptive, or manual voltage modes. If you run your CPU at maximum frequency at all times, then you can use override mode, but if you are going to let the CPU multiplier go up and down according to load, then you will want to set adaptive or offset mode. CPU Mesh/cache/ring voltages are all the same thing and can be set up to 1.3-1.35v to help increase mesh frequency. VCCSA and VCCIO are also from the motherboard (external) and help with memory overclocking. On this platform, VCCSA helps more than VCCIO from what I have seen, if you are trying for a memory OC above 3200MHz, I would start with 1.15v VCCSA and move up, but I wouldn't go over 1.3v for 24/7 use. Some of ASRock's motherboards have an internal VCCSA as well, and you can set that offset to around +0.4v if you are clocking really high. If you are going to increase DRAM voltage manually you need to do it twice, once for channels A and B and once for channels C and D.




CPU Load Line Calibration can help reduce the drop in the input voltage to the motherboard; I prefer the second highest level. On this platform, because power consumption is so high, you will need to increase current limits and any other type of protection mechanisms because you will easily hit their limits. I would not increase switching frequency since that will just increase overall temperature of the VRM. On MSI's motherboard, you should increase the setting called VR 12VIN OCP Expander and CPU overcurrent protection at the same time. You might not want to increase over temperature protections though.




To make the CPU frequency stay stable many people try to disable EIST, but what they don't know is that depending on how the vendor has implemented EIST, it might actually disable your ability to overclock. I would leave Turbo Mode, and EIST (Enhanced Intel Speed Step) enabled.

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