To know your 3D graphic(s) controller(s) working (GPU or/and chipset) with your VGA output you can run the following command :
/sbin/lspci | egrep 'VGA|3D'Example :
/sbin/lspci | egrep 'VGA|3D'
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [GeForce GT 630M] (rev a1)