speed stepping

[Thorsten Johannvorderbrueggen <thorsten.johannvorderbrueggen@t-online.de>]

Hello all,

i have a little "understanding" problem:

Background:
I have a mac mini (1,42GHz) running debian sid and a iBook (Jul05 -->
1,42GHz) running slackintosh. On the iBook also runs powernowd. If i do
a cat to /proc/cpuinfo, i can see, that the cpu speed is 710MHz or
1420MHz. So it seems to work.

Problem:
I compile a kernel on the iBook and on the mac mini. Both with the same
kernelconfig, both start at the same time! --> the iBook take nearly the
double time as the mac mini. The funny think is, that /proc/cpuinfo say
1420MHz! 
After that i did a "accu test": There's no notable different between the
"accu runtime" on 710MHz and 1420MHz (in both test, the iBook did
"nothing", only cursor blincking and gdm running).

Is there're a problem with speedstepping and the new iBooks? I googled
around and foung no hints!

Any suggestions would be fine.

Bye
  Thorsten