Strange motherboard POST issue when disconnecting the power

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fmatthew5876

Member
Mar 20, 2017
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Hey everyone.

I've got a Supermicro MBD-C9Z390-CGW-O. It's a desktop class motherboard.

I have a really strange issue with it. When the system runs, everything is perfectly stable. However if I disconnect the power, the machine has trouble booting.

After disconnecting the power, I turn it on. It will run for a few seconds with no video output, turn itself off. Then it will restart and turn itself back on, no video output, running for longer this time, and then turn itself off. Finally it will turn itself on a 3rd time, and POST successfully, then I get a bios prompt saying the BIOS settings have been reset to their defaults.

This happens every time I physically disconnect the power. If I leave it plugged in and just shut it down, everything works normally.

This is a desktop board with overclock capabilities. If you overclock it too high, it does this exact same behavior. However, I observe this behavior even without touching any BIOS settings. I don't run it overclocked.

I'm thinking maybe it could be the CMOS battery needs to be replaced? Have any of you seen behavior like this before?
 

RolloZ170

Well-Known Member
Apr 24, 2016
5,159
1,549
113
maybe the CLEAR CMOS switch is stuck in on position.
check all jumpers, JPME2, J9701, J97012
set all jumpers t0 default, refering the manual.