Out Of Memory Video after some time

Received 2 crash and popup “Out of Memory Video” playing 3 hours of game
i5 - 16Gb - nvidia 750 ti - all graphics on low - 1400x900 full screem

please check video buffer cache clean on map trasitions.
when i send Alt-tab and back, the first windown contain previous random image already renderized, untill all contents load and update.