• Leaky Ni-Cd clock battery

The Ni-Cd battery may be leaking, risking damage to PCB layers & nearby components. Promptly remove the battery & clean corrosion/alkaline salts from the board. Use white vinegar to dissolve salts, but exercise caution as vinegar can corrode exposed metals. A thorough examination & repair may be needed. Replace battery with guide: https://github.com/wiretap-retro/Not-A-Varta

• 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.