S3 Graphics
That is not nVidia. That is, well, S3 Graphics! That company was manufacturing video cards (with no 3D acceleration I believe) in the 90s. It is possible that the card itself does not support the resolution you want! I do not think there is any independent effort to make a Linux driver for S3's cards. So, you must be stuck with what S3 contributed to Linux... if it ever contributed anything (otherwise you are use the generic "vesa" driver). Sorry.
