Odd hardware problem

[Billy SG McCarthy]

Monday night, I shut my computer down to give it a
rest.  Tuesday I tried to turn it back on, and it
wouldn't.

It won't boot, won't POST, won't even give me the BIOS
screen.  There is power going to the MoBo, and both of
the CD drives, and both HDDs are spinning when I turn
it on; whether or not the IDE cables are connected.

I've tried replacing the BIOS battery, disconnecting
some/all of my IDE drives, cleaning gunk from the CPU
heatsink, removing the graphics card (as it's BIOS
wouldn't show up either).  

I'm at a loss.  It worked fine one day, and the next,
it just sits there and hums.  The HDD activity light
is solid if the IDE cable is plugged in.  I also tried
shorting the CMOS but that hasn't helped either.

Any thoughts?

=====
"What a long strange trip it's been."
--The Grateful Dead--

Kindly yours,
Billy S G McCarthy

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