Adaptive Voltage mode is the standard method to configure the VccIA or VccCORE voltage of Intel CPU cores according their factory-fused voltage-frequency curves.
Override mode is the alternative method of voltage configuration. Override mode specifies a single static voltage across all ratios. It is mainly used for extreme overclocking purposes where stability at high frequencies is the only consideration.
Both override and adaptive mode settings can be configured via the CPU registers. So, in effect, we control the CPU VID request to the voltage controller. This is Intel’s intended way of overclocking. Of course, most voltage controllers also allow independent configuration. For example, they enable us to configure a voltage offset to the requested voltage. It is often unclear from the motherboard BIOSes which method of setting the CPU core voltage we’re using when we type in the desired voltage.
For the purpose of this article, however, let’s ignore the capabilities of the voltage controllers and focus on Intel’s intended way of overclocking.
We can specify a voltage offset for override and adaptive modes. Of course, this doesn’t make much sense for override mode – if you set 1.35V with a +50mV offset, you could just set 1.40V – but it can be helpful in adaptive mode. The entire V/F curve can be offset by up to 500mV in both directions.
Intel offers great granularity for tuning the many V/F curves inside the CPU. Let’s forget about the E-cores and Ring to keep things simple and assume a case where we set a global adaptive voltage for the CPU P-cores. Now let’s dig into what happens when we set a global adaptive voltage.
First, disregarding any user-set global or V/f point offsets, the adaptive voltage set in the BIOS is mapped against what’s called the “OC ratio.” The “OC Ratio” is the highest ratio configured for the CPU.
When you leave everything at default, the OC ratio is determined by the default maximum turbo ratio.
Let’s that the example of the 13700K, so that ratio is 54X, which is the Turbo Boost Max 3.0 frequency. In the case of the 13900K, that ratio would be 58X, which is the Thermal Velocity Boost Frequency. When you manually overclock, the OC ratio is the highest ratio you configure across all the various settings and options.
Second, specific rules govern what adaptive voltage can be set.
A) the voltage set for a given ratio n must be higher than or equal to the voltage set for ratio n-1.
Suppose our 13700K runs 54X at 1.30V. In that case, setting the adaptive voltage, mapped to 54X, lower than 1.30V, is pointless. 54X will always run at 1.30 or higher. Usually, BIOSes will allow you to configure lower values. However, the CPU’s internal mechanisms will override your configuration if it doesn’t follow the rules.
B) the adaptive voltage configured for any ratio below the maximum default turbo ratio will be ignored.
Take the same example of the 13700K, which is specified to run 54x at 1.30V. If you try to configure all cores to 52x and set 1.40V, the CPU will ignore this because it has its own factory-fused target voltage for all ratios up to 54X and will use this voltage. You can only change the voltage of the OC Ratio, which, as mentioned before, on the 13700K, is 54X and up.
C) for ratios between the OC Ratio and the next highest factory-fused V/f point, the voltage is interpolated between the set adaptive voltage and the factory-fused voltage.
Returning to our example of our 13700K specified to run 54X at 1.30V, let’s say we manually configure the OC ratio to be 58X at 1.425V. The target voltage for ratios 55X, 56X, and 57X will now be interpolated between 1.30V and 1.425V.
So, in conclusion.
The adaptive voltage set in BIOS is mapped against the “OC Ratio.” Unless explicitly programmed, the OC Ratio is the highest ratio configured for the CPU across all settings, including by core usage, per core ratio limit, and OCTVB. The voltage for ratios lower than the OC ratio is set either by its factory-fused V/f point or, if there’s no V/f point, interpolated between the next and previous V/f point.