sleep/wakeup, iMac-hardware

FreeBSD is installed on a separate partition apart from macos 10.6.
There is a power meter clamped into the supply line. Normal reading is 85+/- Watt.

With zzz freeBSD goes to sleep. Reading 0 Watt.

Wakeup as follows (no joke!):
1) press ON-button; reading 34+/- Watt.
2) press ctrl+alt+F1; reading increases briefly, then 34 Watt.
3) press ctrl+alt+F6; wait >1 Min !!; reading unchanged.
4) press ctrl+alt+F9; immediately desktop returns with all items working.

Naturally I tried a lot of similar mysterious combinations - to no avail.
Has anyone an idea what is happening there?
Can anyone reproduce that stunt?