A periodic flicker exists in an external Dell ST2410 that is attached to this computer via the DVI connector and, importantly, occurs ONLY since upgrading from Lion 10.7.5 to 10.8.4 one day ago. Besides the flicker, the external display will occasionally go completely blank for 1-2 seconds. This is reproducible (weirdly) when the central air conditioning turns on in my apartment. This does not occur with the internal color LCD. Flicker occurs regardless of whether computer is connected to AC power via magsafe.
Important that it occurs only since 10.8.4; not sure if this existed in previous iterations of OS X.
Disabling automatic graphics switching does not affect the occurrence of the flicker.
System logs do not show anything.
Resolution of external monitor is 1920x1080
Model Name: MacBook Pro
Model Identifier: MacBookPro9,1
Processor Name: Intel Core i7
Processor Speed: 2.7 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 16 GB
Boot ROM Version: MBP91.00D3.B08
SMC Version (system): 2.1f170
Serial Number (system):
Hardware UUID: 7A534DAA-7147-598D-AD15-595884440804
Sudden Motion Sensor:
System Version: OS X 10.8.4 (12E55)
Kernel Version: Darwin 12.4.0
Boot Volume: 500GB SolidState
Boot Mode: Normal
Secure Virtual Memory: Enabled
Time since boot: 1:27
Anyone have any suggestions?