Precision Boost Overdrive is the overclocker’s extension of Precision Boost 2 as it provides us with tools to tweak the Precision Boost 2 algorithm and achieve higher frequencies. The technology was introduced with Ryzen 2000 Zen+ processors. It is important to mention that using Precision Boost Overdrive is a form of overclocking and is therefore not covered by warranty.
Precision Boost Overdrive
If you understand the profound difference in the boost approach of Precision Boost 2 versus the original, you will also understand the opportunity that rises from it. Precision Boost Overdrive allows the end-user to change the power, thermal, and current parameters to provide the Precision Boost 2 algorithm with even more headroom. Precision Boost Overdrive has three main tuning knobs:
Package Power Tracking, or PPT, is the total power the processor can draw from the socket before the boost levels off. Typically, the limiting factor is your CPU thermal solution.
Electrical Design Current, or EDC, represents the maximum peak current the voltage rail can demand under transient conditions for a short, thermally insignificant time. Independent EDC tuning is available for both the VDDCR and VDDCR_SOC voltage rails. Typically, the limiting factor is the choice of VRM components and their maximum rated specification.
Thermal Design Current, or TDC, represents the maximum sustained current the voltage regulator can support. Independent TDC tuning is available for both the VDDCR and VDDCR_SOC voltage rails. Typically, the limiting factor is the choice of VRM thermal solution and the VRM components.
Precision Boost Overdrive Plus
With Zen 2 processors, AMD introduced a slightly updated version of Precision Boost Overdrive, unofficially called Precision Boost Overdrive Plus.
Whereas the original PBO only allowed for adjusting the power and current parameters of the Precision Boost 2 algorithm, PBO+ adds two more tuning knobs: Auto OC and Scalar
AutoOC, later dubbed Boost Clock Override, or Fmax Override, allows the user to override the arbitrary clock frequency limit between -1000 MHz and +200 MHz in steps of 25 MHz. It is available for both the CPU core clock and, if present, the Graphics core clock. It’s important to note that the override only adjusts the upper ceiling of the frequency and doesn’t act as a frequency offset. Ultimately, the Precision Boost 2 algorithm still determines the actual operating frequency.
AutoOC can be most easily explained as a user-configurable version of XFR2. As you remember, XFR allowed the processor to boost higher than the maximum Precision Boost frequency if the CPU temperature was low enough. The maximum boost was 100MHz for Ryzen processors and 200MHz for Ryzen Threadripper processors. With Zen 2, XFR disappears and is replaced by AutoOC. The user can now manually configure the maximum overclock in steps of 25MHz up to 200MHz. It’s important to note that setting 200MHz simply lifts the maximum frequency ceiling but does not guarantee a higher frequency. The effective boost frequency is still governed by the Precision Boost 2 algorithm. The AutoOC feature would later be called Boost Clock Override or Fmax Override.
Scalar is a tool that allows the user to override the warranted silicon stress level, or FIT, to achieve higher frequency. You can adjust the maximum allowed FIT level to 10 times higher than the factory-fused limit. While the tool offers precise granularity, typically, you’ll find the available options to range between 1X and 10X in steps of 1 multiple.Practically, the Scalar is a single factor that, when increased, forces the Precision Boost 2 algorithm to pursue higher voltages more aggressively. As a consequence, the frequency would be higher too.
Precision Boost Overdrive is succeeded by the 2nd generation Precision Boost Overdrive 2.