SE7210TP1-E server board loses memmory

Have a SE7210TP1-E server board and since I added a nvidia ge force 6200  pci graphics card the system reserved 1 gig of ram for it self.

Question is WHY?

Have 4 gig ram onboard, if I unplug graphics card I have 4 gig system ram available again. WHY?

The onboard graphics card is a ATI rage 2 xl chipset with 8 meg ram.

The onboard graphics cant handle video data of today anymore.