Intel OverClocking Thermal Velocity Boost

Overclocking thermal velocity boost, or OCTVB, allows the user to manually configure the Thermal Velocity Boost behavior of Intel CPUs.

Intel Thermal Velocity Boost

In 2018 Intel introduced Thermal Velocity Boost along with the Core i9-8950HK Coffee Lake mobile flagship processor. Thermal Velocity Boost opportunistically increases the clock frequency above the Turbo Boost 2.0 frequencies based on how much the processor is operating below its maximum temperature. The frequency gain and duration depend on the workload, capabilities of the processor, and the processor cooling solution.

For processors that have Intel® Thermal Velocity Boost enabled, the maximum Core Frequency is achieved when the processor is at a pre-specified temperature or lower and turbo boost budget is available. For the 11900K the pre-specified temperature is 70c.

With the introduction of the Intel Cryo Cooling Technology in 2020, Intel opened up the Thermal Velocity Boost configuration to motherboard vendors. Obviously, the Cryo Cooling technology exploits the increased overclocking headroom of much lower operating temperatures.

Overclocking Thermal Velocity Boost Configuration

overclocking thermal velocity boost in asus rog bios

You can use either XTU or, on motherboards that support it, configure Thermal Velocity Boost from the BIOS. The easiest way to understand the Thermal Velocity Boost configuration is by going from top ratio to bottom ratio.

The first column lists the count of active cores, going from 1 active core to 8 active cores with the 11900K.

The second column describes the maximum possible ratio for a particular count of active cores. So, in this example, the maximum ratio for 1 core active is 56 and the maximum ratio for 8 cores active is 53. Since we keep a fixed base clock frequency of 100 MHz, this results in respectively 5.6 GHz and 5.3 GHz.

The third column describes the first temperature offset point. When the CPU exceeds this temperature, it will decrease the ratio of the CPU. In my example, when 4 cores are active, and the CPU temperature exceeds 64 degrees then the CPU will decrease the ratio. Similarly, when the temperature exceeds 52 degrees and 8 cores are active, the CPU will also decrease the frequency.

The fourth column describes the ratio offset for the temperature configured in the third column. So, when the CPU temperature exceeds 64 degrees and 4 cores are active, the ratio will decrease by 1. 54 minus 1 equal 53. So, the CPU will run the 4 cores at 5.3 GHz.

The fifth column is an additional temperature offset point. The function is the same as the first temperature offset. While on Comet Lake the ratio offset for temperature B was fixed to 1, on Rocket Lake it is also configurable.

So, in this case, when 2 cores are active the frequency will be 5.6 GHz. However, if the CPU temperature exceeds 20 degrees, then the frequency will be 5.5 GHz. And if the temperature exceeds 45 degrees, the frequency will be 5.5 GHz.

As you can see, the OCTVB function configures the ratio offsets on a by core usage basis. However, as we know Rocket Lake introduced the Per Core Ratio Limit feature. From testing with different tools, it appears that OCTVB also supports Per Core Ratio offsets. The way it negotiates which ratio offset to apply in a given situation is to pick whichever is worse: the ratio offset as determined by the by core usage or the per core ratio limit offset.

overclocking thermal velocity boost per core on rocket lake

The functionality to set OCTVB on a per core ratio limit is not exposed in the Intel documentation and is unlikely to end up in any BIOS. Maybe we will see it pop up in the future.

Intel OverClocking Thermal Velocity Boost in SkatterBencher Guides

We use Intel OverClocking Thermal Velocity Boost in the following SkatterBencher guides:

  • SkatterBencher #25: Intel Core i9-11900K Cryo Overclocked to 5600 MHz (link)
  • SkatterBencher #19: Intel Core i9-10900K Overclocked to 6000 MHz (link)