Pentium III (Socket 370) and Pentium III Xeon (Slot 2) boards - I'm cringe now.
Also featured: Stinkin' gigantic Intergraphic Wildcat 4000 graphics card (10/1998). Two board stack (1xAGP, 1xPCI), 16MB Framebuffer, 64MB texture RAM. Intended to compete with SGI's early PC-based offerings.