[Cube] Cube won't recognize hard drive

[AndrewAA]

Hello  All
I've got a stock cube 450 that has stopped working.
It wouldn't start from the hard drive or ,  just shows the question  
mark folder.
When I put the hard drive in an external firewire case Diskwarrior  
reported problems with the boot partition.
So I erased and did a fresh install of 10.4 and reinstalled the drive  
but it still wouldn't boot.
However it will boot with the same drive in an external firewire case.
The same drive will also boot up in my other cube.
The cube won't boot into target disk mode, I hear the hard drive spin  
up, the screen flickers then the power switch light switches off.
Trying to boot to a CD produces the same effect.
I'm thinking the IDE controller is fried.
I had a momentary inspiration to upgrade the CPU hoping that would  
fix the problem but looking at the machine I'm thinking that the hard  
drive plugs into the motherboard and replacing the CPU probably  
wouldn't replace the IDE controller.

Any thoughts?
Anyone got a spare motherboard?
Anyone interested in a cube project?

Andrew in Ann Arbor