Briefly my Mac Pro (4,1 Early 2009 ) stopped booting which I eventually traced to the plastic clip holding the north bridge down failing. Seems to be a common issue.
Replaced the clips and now it will boot again and is stable but refuses to run the 2nd CPU. Kernel boot messages show it's there but disabled.
Apple hardware test gives error of 4SNS/1/40000000: TCBC-252:000 which from various sites on the net I understand to mean
4SNS - Sensor TCBC |----- Temperature |---- CPU |--- CPU B ? |-- C ?`
Any idea on the numbers ?
Can anyone help me diagnose here, is it new Heatsink time or new Logic board time. Neither is great but a heatsink is much cheaper than a logic board.Is it something else that's fixable ?
- Both CPUs verified good in socket A.
- All RAM verified good in Socket A RAM slots.
- No diagnostic LEDs lit.
- New thermal paste everywhere
- SMC reset
- PRAM reset
EDIT: RAM Clarification EDIT: Things done Thanks