CPU温控及节电技术

1、CPU温控及节电技术OverviewThermal Control Technic “Thermal ThrottlingPower Saving Technic “Performance State Thermal ThrottlingIntel Pentium 4 and AMD Athlon XP CPU both have a set of thermal Diode to detect CPUs temperature To implement “Thermal Throttlingfunction, they set a mechanism between CPU internal

2、 frequency and external frequency ,plus the diode together named “Thermal Monitor In the case of normal CPU temperature “Thermal Monitor would not affect CPUs host frequencyWhen the CPU is hot than critical temperature, “Thermal Monitor would generate a “Internal clock duty cycle to ignore some CPUs

3、 normal internal clock.So the CPU performance will poor and the temperature will fall together.Implement On VIA PlatformVIA VT8237 SB provide a “Internal clock duty cycle named “STPCLK#At software side should set “duty cycle percent first, then use real time detect and control to make throttling ena

4、ble at critical time. Performance StateAccording to ACPI 3.0 spec,OS could detect the systems workload through BIOS and device driver.According to workload,APCI specified the CPU P-state(performance state) from P0、P1 to Pn CPU speed:P0(full speed)P1Pn Core voltage:P0P1PnIntel Pentium M 1.6GHz P-Stat

5、e structure，lowest X6VIA C7M 1.6GHz P-State structure，lowest X4Enhanced Intel SpeedStep technology (EIST)AMD Cool N QuietVIA Enhanced Power Saver C7M Lower power consuming&Lower P-stateBack GroundGenerally, processor change from one P-state to another state needs a complicated process Pause CPU=Reset PLL=CPU cl