This is a 4x4 Desktop, which uses the well-recognized "Frog Design" design. It includes a single 3.5" floppy drive and a single CD-ROM drive - as well as an empty 5.25" drive bay. Rarely, these machines were seen with dual CD-ROM drives. The 3x3 Desktop removes the second 5.25" drive bay.
This case design was also used by Zenith Data Systems for their desktop computers. Little is known about the Zenith models.