updated 10:25 pm EST, Wed December 16, 2009
Bug apparently affecting Nehalem-based systems
A larger number of Mac Pro owners have reported problems with excessive CPU heat while simply playing audio, according to several threads on Apple's Support forums and Macrumors forums. Although playing MP3s through iTunes only utilizes a small fraction of the available CPU resources, users are claiming that the core temperatures soon approach the operating limits.
Users have allegedly observed power consumption start at 3-5W at idle, with audio playback quickly causing a jump up to 50W. As the CPU cores draw additional power, the temperature rises into the range of 60ºC or higher for many users. The problem reportedly persists with any function utilizing audio, including system sounds and even external devices.
Although the cause of the excessive power drain remains unclear, the issue appears to be limited to the latest Nehalem-based Mac Pros. Switching between Leopard and Snow Leopard does not provide a remedy. The Mac OS X operating system is nonetheless believed to be partially responsible, as the temperature and power drain have dropped to normal levels for users playing audio in Windows via Boot Camp.
Many users have voiced frustration that Apple has yet to acknowledge the issue or release a software or firmware update containing a fix.