Glad you figured it out and fascinating story. Have heard of and have had some odd issues with case connectors before but never a speaker, nope don't think I ever heard about that until now.

mrfusion92 wrote on 2023-05-26, 17:34:

And we have a winner! […]
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konc wrote on 2023-05-26, 08:28:

I don't know how relevant this is for your case (pun intended!), but I was puzzled once by a... broken switch, a stuck reset switch. Of course this can only be a possibility to consider if you are not connecting the switches when outside of the case but you are connecting them when inside it.

And we have a winner!

Well it wasn't the switch but this pointed me in the right direction since it was.... the speaker! Yes when the speaker is connected the motherboard doesn't post. Tested three times because I really couldn't believe it.

And indeed outside the case I NEVER tested with the speaker but inside the case I ALWAYS plugged it.

I'm really having a good laugh out of it.

Reminds me of the time I was troubleshooting a motherboard (on a cardboard box on a table) and at some point it was dead. Tried things left and right and it just wouldn't come back to life no matter what I did.
Then saw that apparently the power cable had come loose... ....... ............ ...................... -_-
So of course it wouldn't power on anymore! 😂
Plugged it back in and then powered on the board it worked just fine 😅

Stuff like that happens 😋