[Windows 8 General] Wootever:
It is located at Advanced -> CPU Configuration -> TCC Activation Offset, the base value is 95°C and is subtracted by the offset.

For example: 95°C - 25°C = 70°C; the offset is 25.

This is all intended (excluding the undervolting reset, probably a ThrottleStop issue), the TCC throttling mechanism is more reliable and intelligent than the other mechanisms.

It keeps both the GPU and CPU at the desired temperature of 65°C without any TDP hard lock or intense frequency jumps.

Edit:

more information about TCC:

Thermal Control Circuit (TCC) Activation Offset
TCC Activation Offset can be used to activate the Adaptive Thermal Monitor at
temperatures lower than TjMAX. It is the preferred thermal protection mechanism for
Intel Turbo Boost Technology 2.0 operation since ACPI passive throttling states will
pull the processor out of turbo mode operation when triggered. An offset (in degrees
Celsius) can be written to the TEMPERATURE_TARGET (0x1A2) MSR, bits [29:24]. This
value will be subtracted from the value found in bits [23:16]. The default offset is
0 °C, TCC activation will occur at TjMAX. The offset should be set lower than any other
protection such as ACPI _PSV trip points.

Adaptive Thermal Monitor
The purpose of the Adaptive Thermal Monitor is to reduce processor core power
consumption and temperature until it operates at or below its maximum operating
temperature. Processor core power reduction is achieved by:
• Adjusting the operating frequency (using the core ratio multiplier) and voltage.
• Modulating (starting and stopping) the internal processor core clocks (duty cycle).
The Adaptive Thermal Monitor can be activated when the package temperature,
monitored by any digital thermal sensor (DTS) meets or exceeds its maximum
operating temperature. The maximum operating temperature implies either maximum
junction temperature TjMAX, or TjMAX minus TCC Activation offset.
Exceeding the maximum operating temperature activates the thermal control circuit
(TCC), if enabled. When activated, the thermal control circuit (TCC) causes both the
processor core and graphics core to reduce frequency and voltage adaptively. The
Adaptive Thermal Monitor will remain active as long as the package temperature
exceeds its specified limit. Therefore, the Adaptive Thermal Monitor will continue to
reduce the package frequency and voltage until the TCC is de-activated.
TjMAX is factory calibrated and is not user configurable. The default value is software
visible in the TEMPERATURE_TARGET (0x1A2) MSR, bits [23:16]. The
TEMPERATURE_TARGET value stays the same when TCC Activation offset is enabled.
The Adaptive Thermal Monitor does not require any additional hardware, software
drivers, or interrupt handling routines. It is not intended as a mechanism to maintain
processor TDP. The system design should provide a thermal solution that can maintain
TDP within its intended usage range.

Thermal Solution Design and PROCHOT# Behavior
With a properly designed and characterized thermal solution, it is anticipated that
PROCHOT# will only be asserted for very short periods of time when running the most
power intensive applications. The processor performance impact due to these brief
periods of TCC activation is expected to be so minor that it would be immeasurable.
However, an under-designed thermal solution that is not able to prevent excessive
assertion of PROCHOT# in the anticipated ambient environment may:
• Cause a noticeable performance loss.
• Result in prolonged operation at or above the specified maximum junction
temperature and affect the long-term reliability of the processor.
• May be incapable of cooling the processor even when the TCC is active
continuously (in extreme situations).

Use Right click on ISD_INFInstall.inf -> Install.