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My T400 screen switches off then turns back on when I unplug the AC adapter or when I plug in the AC adapter.


This issue is caused when the Video Adapter is shifting refresh rate from 60Hz to 50Hz and vice versa.


If you prefer the screen not to blink you may do so by changing the settings in your Lenovo Power Manager.


  1. Open Lenovo Power Manager
  2. Go to the Power Profile which you have selected then Idle Timers
  3. Set the "Lower display refresh rate" to "Never" for both AC and battery.
  4. Press OK to save.






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