The Frequency Behavior of AMD's CPUs is complex and is governed by multiple mechanisms that perform dynamic frequency scaling based on the available headroom.
AMD has implemented a number of mechanisms into their architectures to extract additional performance through higher frequency whenever the power and thermal budgets allow.
- Cool'n'Quiet - Introduced with K8 in 2003
- Turbo Core - Introduced with K10(Thuban) in 2010
- Precision Boost - Introduced with Zen in 2017
- eXtended Frequency Range (XFR) - Introduced with Zen in 2017
- Mobile eXtended Frequency Range (mXFR) - Introduced with Zen-based Mobile in 2017
This list is incomplete; you can help by expanding it.
Under Precision Boost, the turbo was defined per core. for AMD's Ryzen brand (i.e. Ryzen 3, Ryzen 5, and Ryzen 7, the maximum turbo frequency is govern by three parameters: All Boost, Max Turbo, and XFR Boost. With only one to two active cores, the processors can hit the Max Turbo. However, anything in excess of two active cores, the processor drops to an All Boost frequency. For Threadripper, the Max Turbo was defined for 4 active cores or less and for AMD's EPYC brand, the Max Turbo is defined for 12 or less active cores.
With the introduction of Precision Boost 2, the per-core definition was eliminated. Instead, the processor will automatically allow turbo for as many cores as the power budget allows.
- Intel's Frequency Behavior