Symptoms
X220 CPU clock rates may throttling down to lowest state even when a max performance profile is used, even while plugged in when using the 65W adapter. Unlike other power controls in Power Manager / BIOS, CPU Power Management (and Speedstep) can only be turned on/off globally, not separately by power source.
Diagnosis
X220 ThinkPads using the 65W adapter and BIOS versions prior to 1.21 could exhibit these symptoms.
No throttling was evident when using 90W AC adapters.
Solution
The cumulative fix to address the semi-perma throttling described above is contained in BIOS 1.21 and later - see links below. This also includes the fixes for the perma-throttling symptoms previously resolved in version 1.19.
BIOS 1.21 for X220
BIOS Utility here
BIOS text here
BIOS ISO here
BIOS ISO text here
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CHANGES IN THIS RELEASE
Version 1.21
[Important updates]
Nothing.
[New functions or enhancements]
- Improved system performance when heavy program is executed with 65W AC adapter.
- Improved system boots time.
- Disabled keyboarding while the lid was closed to avoid unexpected key input
when the computer was held with the lid closed.
[Problem fixes]
- Fixed an issue where the computer might not be booted from bootloader program.
- Fixed an issue where a 1820 error might occur at power-on when the external
fingerprint reader device was attached to the computer while the integrated
fingerprint reader was disabled in the ThinkPad Setup.
- Fixed an issue where the computer might fail to boot when connected the
Smartphone with the USB port.
- Improved cooling fan noise.
- Corrected spelling mistakes in BIOS setup menu.
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