35-198 Vol. 3C
MODEL-SPECIFIC REGISTERS (MSRS)
690H
1680
MSR_CORE_PERF_LIMIT_REA
SONS
Package
Indicator of Frequency Clipping in Processor Cores (R/W)
(frequency refers to processor core frequency)
0
PROCHOT Status (R0)
When set, processor core frequency is reduced below the
operating system request due to assertion of external PROCHOT.
1
Thermal Status (R0)
When set, frequency is reduced below the operating system
request due to a thermal event.
3:2
Reserved.
4
Graphics Driver Status (R0)
When set, frequency is reduced below the operating system
request due to Processor Graphics driver override.
5
Autonomous Utilization-Based Frequency Control Status (R0)
When set, frequency is reduced below the operating system
request because the processor has detected that utilization is
low.
6
VR Therm Alert Status (R0)
When set, frequency is reduced below the operating system
request due to a thermal alert from the Voltage Regulator.
7
Reserved.
8
Electrical Design Point Status (R0)
When set, frequency is reduced below the operating system
request due to electrical design point constraints (e.g. maximum
electrical current consumption).
9
Core Power Limiting Status (R0)
When set, frequency is reduced below the operating system
request due to domain-level power limiting.
10
Package-Level Power Limiting PL1 Status (R0)
When set, frequency is reduced below the operating system
request due to package-level power limiting PL1.
11
Package-Level PL2 Power Limiting Status (R0)
When set, frequency is reduced below the operating system
request due to package-level power limiting PL2.
12
Max Turbo Limit Status (R0)
When set, frequency is reduced below the operating system
request due to multi-core turbo limits.
13
Turbo Transition Attenuation Status (R0)
When set, frequency is reduced below the operating system
request due to Turbo transition attenuation. This prevents
performance degradation due to frequent operating ratio
changes.
15:14
Reserved
Table 35-28. MSRs Supported by 4th Generation Intel® Core™ Processors (Haswell microarchitecture) (Contd.)
Register
Address
Register Name
Scope
Bit Description
Hex
Dec