Battery drain while connected to power?

[glx]

Hi,
I noticed, that my SP3 looses some percent of battery when it is under heavy load although it's connected to power all the time, examply some time of gaming.
I start at 'Charged (100%)' and when I return to the desktop after maybe one hour, the battery-symbol says 'Charging (95%)'.
Is there anyone else with that problem? Is the power-adapter too weak or may the problem be the surface itself? I have the i7-version.

 

[theveterans]

Same here. Playing steam games consume more power than what the adapter can provide resulting to battery drain