Everything that can be pulled out of the case has been removed and the motherboard laid bare. One by one I added components to the mobo...the bare minimum required to get the system booting.
Hard Drive
USB/display output module
WiFi/Bluetooth module
Magsafe
booted up...all good except all of a sudden I have 'kernel_task' taking up 150% cpu and the thing is running slow as a dog.
A bit of research indicates this is a thermal issue but what was causing it? The CPU wasn't overheating yet OS X thought it was...the heatsink was in place and barely warm to the touch.
Looking back at the remaining unattached components I noticed a trace on the ribbon cable that leads to the IR sensor and power LED. The trace went all the way to the front of the chassis, connected to what looked like a small resistor then looped back to the motherboard.....whatever it was (thermostat perhaps), not having it connected was affecting the thermal logic because as soon as it was connected the CPU returned to idle.
I've also dismantled a white Apple keyboard and have an initial layout of components. So far things are looking pretty good in terms of space and where ports will be located. The only major sticking point at the moment is that the power button is part of the keyboard circuitry so unless I use the Air's keyboard I don't get a power switch.
Onward and upward
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