Target Disk mode heat issues?

[Gregory P. Perez]

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?

Thanks,
Greg