Yes, that's a fairly common theme while in TDM. My best guess is that open firmware, in order to save space and money in manufacturing, doesn't have the code to control processor power saving. So, instead of the computer powering down execution units that aren't needed (or even turning off the whole processor for short periods of time), everything is running at 100% all the time, generating a lot more heat. Kynan Shook kshook at mac.com http://homepage.mac.com/kshook/index.html "Gregory P. Perez" <gpp7824 at mac.com> writes: > I'd like to use my powerbook in target disk mode for long periods of > time. > But, after about 10 minutes of use (not actively transferring files, > just > idle and waiting) the fan turns on. After about 30 minutes of use the > fan > steps to jet propulsion levels. However, the fan will not normally > come on > at all if I'm simply using the machine in stand-alone format. Is there > something about being in target disk mode that promotes greater heat? > Do > others observe the same?