Intel 2955U CL8064701523900 Data Sheet

When operating in turbo mode, the processor monitors its own power and adjusts the

turbo frequencies to maintain the average power within limits over a thermally

significant time period. The processor calculates the package power that consists of

the processor core power and graphics core power. In the event that a workload

causes the power to exceed program power limits, the processor will protect itself

using the Adaptive Thermal Monitor.

Illustration of Intel Turbo Boost Technology 2.0 power control is shown in the

following sections and figures. Multiple controls operate simultaneously allowing for

customization for multiple system thermal and power limitations. These controls allow

for turbo optimizations within system constraints and are accessible using MSR, MMIO,

or PECI interfaces

The package power control allows for customization to implement optimal turbo within

platform power delivery and package thermal solution limitations.

POWER_LIMIT_1 (PL1)

14:0

SKU TDP

• This value sets the average power limit over a long time

period. This is normally aligned to the TDP of the part and

steady-state cooling capability of the thermal solution. The

default value is the TDP for the SKU.

• PL1 limit may be set lower than TDP in real time for specific

needs, such as responding to a thermal event. If it is set

lower than TDP, the processor may require to use frequencies

below the guaranteed P1 frequency to control the low-power

limits. The PL1 Clamp bit [16] should be set to enable the

processor to use frequencies below P1 to control the set-

power limit.

• PL1 limit may be set higher than TDP. If set higher than TDP,

the processor could stay at that power level continuously and

cooling solution improvements may be required.

POWER_LIMIT_1_TIME
(Turbo Time Parameter)

23:17

1 sec

This value is a time parameter that adjusts the algorithm

behavior to maintain time averaged power at or below PL1. The

hardware default value is 1 second; however, 28 seconds is

recommended for most mobile applications.

POWER_LIMIT_2 (PL2)

46:32

1.25 x TDP

PL2 establishes the upper power limit of turbo operation above

TDP, primarily for platform power supply considerations. Power

may exceed this limit for up to 10 ms. The default for this limit is

1.25 x TDP; however, the BIOS may reprogram the default value

to maximize the performance within platform power supply

considerations. Setting this limit to TDP will limit the processor to

only operate up to the TDP. It does not disable turbo because

turbo is opportunistic and power/temperature dependent. Many

workloads will allow some turbo frequencies for powers at or

below TDP.

Mobile 4th Generation Intel

®

 Core

™

 Processor Family, Mobile Intel

®

 Pentium

®

 Processor Family, and Mobile Intel

®

 Celeron

®

Processor Family

Datasheet – Volume 1 of 2

July 2014

60

Order No.: 329001-007