iMac (27-inch, Mid 2010) Symptom Charts — Mechanical 118
2010-09-09
Mechanical

Noise/Hum/Vibration

Unlikely cause: LCD panel, glass panel, enclosure, cables
Quick Check
Symptoms Quick Check
Noise/Hum/Vibration
• Buzzing noise
• Rattling noise
• Ticking noise
• Squeaking noise
1. Verify that the vents on the bottom and
back of the system are free of dust and other
obstructions that might inhibit proper airow
through the system.
2. Launch Applications/Utilities/Activity Monitor.
Determine whether an application or process is
consuming a high percentage of CPU bandwidth.
CPU-intensive applications can cause the fans
to run fast in order to maintain the proper
internal system temperatures. If needed, quit the
application or restart the system to resolve the
issue.
3. Eject optical media from optical drive. Out-of-
balance optical media can generate audible
noise. To resolve try a dierent brand of media.
For additional information, go to Optical Drive
Noisy symptom ow.
4. Tilt display to hinge limits to determine if
mechanical noise is generated by the hinge
mechanism. For additional information, go to
Stand/Hinge Issues symptom ow.
5. Play sound sample at loud and soft volume
levels to determine if the noise is caused by the
left/right speakers or the amplier circuit. Plug
external headphones to identify whether the
noise comes from audio out or from other source.
For additional information, go to Audio: Built-in
Speakers Have Distorted Sound symptom ow.
6. Adjust the display brightness to determine
whether the noise is related to the brightness
level. For additional information, go to Noise/
Unstable Flickering symptom ow.
7. Run latest available Apple service utilities.