The Electrical Model
2.1 SVID, AC, DC and VRM Output
PDF · 7Page 7Keep three levels distinct: the processor generates a request, the VRM physically powers the CPU, and monitoring shows the available telemetry. Using the same units does not make these quantities interchangeable.
| Element | Role in This Method |
|---|---|
| V/F and SVID | V/F provides the basis for the relationship between frequency and voltage; SVID carries commands and data between the CPU and VRM. Other conditions also affect the operating request. |
| IA AC Load Line | A parameter for load-dependent adjustment of the request. Reducing it is used here for undervolting; it is not a fixed offset to the entire V/F curve. |
| CPU LLC | Changes the load-line characteristic of the VCCCORE VRM. Stronger compensation usually reduces steady-state droop, but changes transient response. |
| IA DC Load Line | A parameter in the load-dependent droop model used by the processor for voltage and power accounting. It is not an IOUT adjustment or a separate undervolt. |
| Core VID | VID reported by the CPU. Not a physical Vcore measurement, and not necessarily a raw command that can be inserted directly into a VRM calculation. |
| VOUT / Vcore | VOUT is a voltage reading from VRM telemetry; Vcore Die Sense is a separate motherboard measurement channel. Their agreement must be checked on the specific system. |
| CEP | This protection responds to droop relative to an internal threshold and may limit the load. An absence of errors does not rule out performance loss caused by its intervention. |
2.2 What Can and Cannot Be Calculated
PDF · 8Page 8Steady-State Operation
With adaptive control, the command itself changes with frequency, temperature and load. Dividing the voltage difference between idle and a stress test by the current difference, without controlling the request, therefore does not isolate the load-line resistance.
| Quantity | What Is Actually Known | What It Does Not Establish |
|---|---|---|
| DC = 0.73 mΩ | The DC value adopted for LLC5 from Table 3.2; also used in my profile | A table value does not replace a measurement of transient response |
| IOUT = 244 A | This Current reading is present in the screenshot | It does not establish equality with the internal current estimate used for AC compensation |
| Core VID ≈ VOUT | Readings are close in one operating condition | No proof of exact DC calibration or an absence of overshoot |
| HWiNFO AC/DC | Readback of programmable parameters, when available | Not a direct hardware measurement of power-rail resistance |
Why the calculated 93 mV is not a measured undervolt
The arithmetic 244 A × (0.73 - 0.35) mΩ = 92.72 mV is correct. However, it describes a conditional case in which the current used for AC compensation is assumed to be 244 A and all other conditions are equal. These assumptions cannot be verified from the screenshot. The number is therefore not used to calculate ready-made AC presets or to promise identical VOUT at different LLC levels.
Handling DC in Practice
- Select LLC and set the corresponding DC from Table 3.2. After boot, check the AC/DC values actually applied; Auto for DC is acceptable if readback shows the required table value.
- After changing LLC, replace DC with the value for the new level and retune AC. Keep DC fixed when tuning AC or SVID offset: it is not an additional undervolting control.
- Do not change CPU Current Reporting to hide power consumption. An incorrect DC model may indirectly change clocks through PL enforcement.
- Measuring the physical load-line and fast overshoot requires suitable equipment. A software log helps check behavior, but does not replace that measurement.