• 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

486SX: J6 2-3; J7 open 486DX: J6 1-2, 3-4; J7 closed JP7 open (default) runs the system bus at 1:1 the oscillator. With it closed, it runs at 1:2 the oscillator (divided in half) so a 32MHz osc gives 16MHz, etc.