T520 Backlight pulse - normal?

[TrailRunner]

Just setting up a new T520. When running on battery the sceen backlight exhibits a strange behavior.

1) Looking at Win 7 desktop the backlight is steady
2) Click on Windows Start menu and the backlight will pulse for 2 or 3 beats, looks likes it getting a tiny bit brighter
3) After the 2 or 3 pulses the backlight is steady
4) Click off Windows Start menu and the backlight will pulse for 2 or 3 beats, looks like its getting a tiny bit dimmer
5) After the pulsing the backlight is steady

Same behavior happens when I open/close a single app that is not fullscreen.

Easier to see the pulsing at a brightness of 10 or less. Does not happen at a brightness of 15.

Does not happen when running on AC.

[TrailRunner]

I turned off the Intel graphics power saving feature and the pulse is gone.

http://www.istartedsomething.com/200907 ... g-feature/