iMac (27-inch, Mid 2010) Symptom Charts — Startup and Power 40
2010-09-09
3) Power-related system shut downs:
• External power source was removed.
Power-related shut downs are due to power management, poor connections, or defective
power sources.
Suggested steps for troubleshooting are :
• Reset the SMC: Refer to: kBase #HT3964: Intel-based iMac: How to reset the System
Management Controller
• Verify the following cables are securely connected: AC power cable, AC inlet, and DC power
supply cable connections to logic board
4) Hardware-related system shut downs:
• One of the temperature sensors reached a specied temperature limit
• One of the voltage sensors reached a specied voltage limit
• One of the current sensors reached a specied current limit
These shut downs are due to temperature, voltage, current, fan speed or other hardware related
sensor values getting out of range.
Suggested steps for troubleshooting are :
• Check for all sensors connections and values using the latest available Apple service utilities
and locate sensors using table in the General Troubleshooting chapter
• Check /listen for fan(s) operation
• Check cleanliness of the heatsink ns and the air ow,
• Check for correct seating of the heatsink on logic board and presence of thermal material.
For additional information refer to the Intermittant Shutdown table on the next page.