Hi, somehow reached this thread.
P4 has 2 special pins: VccSense and VssSense.
VCCSENSE - Output VCCSENSE is an isolated low impedance connection to processor core power (VCC). It can be used to sense or measure power near the silicon with little noise.
VSSSENSE - Output VSSSENSE is an isolated low impedance connection to processor core VSS. It can be used to sense or measure ground near the silicon with little noise.
If one makes precision measurement of resistence from that pin to voltage regulator (with CPU onboard, unpowered), one can use that resistence as a known shunt resistor. During operation, measuring voltage on these pins and voltage reg must give you exact voltage drop across the vcore power path, thus it must be possible to calculate power consumption. Vss might be even well suited to be wired directly into analog input of a sound card if that supports DC input.
Wouldn't that be enough to get decent measurement of core power consumption?
Even if voltage drop along the Vcore path might include power going out the cpu via data/address pins, Vss would include only power dissipated inside the core, thus should be representing 100% of CPU heat output. No?
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