• Expansion slots are on proprietary riser

The listed slots are on the riser card that came with the motherboard.
If you have this board make sure you have the riser for it.

• As with many Compaq systems from this era, the BIOS setup is on a hidden partition on the harddisk. If you get a system with the harddisk still operable, BACKUP THIS DIRECTLY. It is not fun recreating it from the setup floppies.
• SCSI controller may be fussy about what model harddisk you fit, make sure the termination is set properly on all parts of the chain.
• Riser card must be fitted, otherwise board will not start. Has 4 PCI + 2 ISA (one ISA and one PCI are shared)
• VRM spare part NO.: 299306-001
• The riser board's edge connector can easly loose good electrical contact with slot. Use of deoxit is advisable.
• RAM memory should be populated in kits of 2 stick each time. Layout matters - refer to manual.
• The board uses Compaq Highly Parallel System Architecture with Dual Memory Controllers Architecture.
• BIOS chips: TI TMS28F020 + COMPAQ 299377-003
  Driver page (archived)
  Setup&Diagnostics Guide (archived)