Intel Turbo Boost 2.0 Technology

Intel Turbo Boost 2.0 Technology allows the processor cores to run faster than the base operating frequency when the processor works below its rated power, temperature, and current specification limits. The ultimate advantage is opportunistic performance improvements in both multi-threaded and single-threaded workloads.

The Turbo Boost 2.0 algorithm works according to a proprietary EWMA formula. This stands for Exponentially Weighted Moving Average. There are 3 parameters to consider: PL1, PL2, and Tau.

  • Power Limit 1, or PL1, is the threshold the average power will not exceed. Historically, this has always been set equal to Intel’s advertised TDP. PL1 should not be set higher than the thermal solution cooling limits.
  • Power Limit 2, or PL2, is the maximum power the processor can use for a limited amount of time.
  • Tau, in seconds, is the time window for calculating the average power consumption. The CPU will reduce the CPU frequency if the average power consumed is higher than PL1.
turbo boost 2.0 algorithm

A significant change from any previous Intel Core processors is that from Alder Lake onwards, at least for the K-SKU CPUs, PL1 is by default equal to PL2. This differs from before, where PL1 would equal the TDP, and PL2 would range from 200 to 250W. This change effectively means that Intel has enabled near-unlimited peak turbo by default!

turbo boost 2.0 alder lake

The maximum performance is, therefore, entirely limited by the capabilities of your cooling solution. If your cooling solution is insufficient, the processor will reduce the operating frequency at the maximum allowed temperature or TjMax. For Intel CPUs, that’s typically at 100 degrees Celsius.

Unleashing Turbo Boost 2.0

Most, if not all, high-end motherboards will unleash the Turbo Boost 2.0 parameters out of the box. Each vendor has their own feature to return to the default values.

  • ASUS MultiCore Enhancement is a single BIOS option that removes all limits constraining the Turbo Boost 2.0 algorithm. Effectively, it allows the CPU to run at maximum turbo boost frequencies indefinitely.
  • GIGABYTE’s Turbo Power Limits “Intel POR” setting forces the Turbo Boost 2.0 power limits to default
  • MSI’s CPU Cooler Tuning option on MSI motherboards allows you to unleash the Turbo Boost power limits. Set the option to Water Cooler and enjoy the maximum performance.

Adjusting the power limits is strictly not considered overclocking, as we don’t change any of the CPU’s thermal, electrical, or frequency parameters. Intel provides the Turbo Boost parameters as guidance to motherboard vendors and system integrators to ensure their designs enable the base performance of the CPU. Better motherboard designs, thermal solutions, and system configurations can facilitate peak performance for longer.

Diagnosing Turbo Boost 2.0 Performance Related Issues

I discussed how we can use HWiNFO to diagnose Turbo Boost 2.0 related performance issues in SkatterBencher #65. We can use HWiNFO to identify what is limiting our Turbo Boost 2.0 performance. The objective as an overclocker is to have the Turbo Boost performance limited only by the Max Turbo Limit. That is the maximum CPU ratio configured in the BIOS, and we can override that to achieve higher frequencies and performance.

turbo boost 2.0 max turbo limit

Let’s see how things work in the real world. We use Prime95 to push the workload and track the performance behavior in HWiNFO. When the system is idle, we can see Max Turbo Limit triggered.

When we launch Prime95 with all cores enabled, we find that quickly the Thermal Event performance limiter is triggered due to the CPU temperature. We find that the PL1 performance limiter is active a few moments later.

turbo boost 2.0 thermal event

The solution for the latter is pretty simple: increase the PL1 limit. We go into the BIOS and program it to the maximum value of 4095.875W.

We then re-run Prime95 and find that a new performance limiter is activated: PL2 or PL3. So, we go back into the BIOS and program PL2 to its maximum value of 4095.875W.

turbo boost 2.0 power limit 2

We re-run Prime95 and find that a new performance limiter is activated: Electrical Design Point/Other, which includes ICCmax and PL4. So, we go back into the BIOS and program ICCmax to its maximum value of 1023A. We then re-run Prime95 and find that the same performance limiter is activated when we enable AVX. So, we go back into the BIOS and program PL4 to its maximum value of 4095.875W.

turbo boost 2.0 electrical design point

We re-run Prime95 and find that a new performance limiter is activated: VR TDC. So, we go back into the BIOS and program TDC Current Limit to its maximum value of 4095.875A.

turbo boost 2.0 vr tdc

After these changes, the only performance limiters still triggered are the Thermal Event, in case our CPU hits the TjMax, or Max Turbo Limit.