On your accelerator/combo card, you've got a SCSI bios chip. Which revision is it? Usually labeled on the chip itself, socketed and nearest to the SCSI bus (or output in the rear). If you have an older version than 4.5, your GVP card WILL "see" the full GB range of the entire HD and even let you "partition" it, but you will not get the familiar NDOS:

icons on the desktop that would allow you to normally format.
If anyone knows of a software workaround that would be great, but I do not believe one exists. The regular ones like IDEFix, fudging with Mountlist, etc., do not work. You must have an updated SCSI chip in your GVP for monstrous drives to work properly.
BTW: Of curiosity, I bet your second partition is slightly larger than 4gb. Get that down to 3.9gb and see if its icon pops up on the desktop...