Situation: My PC is dead in the water. Both power buttons (Case/MB) have no effect. If I pull the power cable, reset CMOS, reconnect the power cable, then press either power button the PC fires right up. The system operates normally once running, however neither power button will shutdown the PC. I use the Power button on my keyboard to shutdown.
Question: What causes a motherboard to require a CMOS reset in order to power on? What is on the CMOS that physically denies power for startup?
- This issue was sudden onset, meaning no changes to hardware, software, power sags, brownouts, overloads, etc. prior to symptoms.
- All components have been voltage tested with a VOM. The wall outlet, PSU, CMOS battery, MB, etc. all check out.
- I have tried alternate PSU & RAM modules. No effect on symptoms.
- Running system with bare minimum hardware has no effect on symptoms.
- I have not flashed the BIOS/CMOS yet. No sense doing this unless I'm positive it's the solution.
- No signs of grounding, charing, blown capacitors, etc.
- PC is custom. MB == Asrock 870 Extreme 3. PSU == XFX Black Edition 750w. These details are a non-factor as I've seen many blogs featuring similar issues with different systems. None of which provided a solution.