I now tried with the settings mentioned in the last post - same effect.
Spread spectrum is disabled and all PCI clocks are at default.
The values are based on the BIOS and seem to be slightly lower when measured with another program.
A question: Should Intel EIST bei disabled or not (I tried both, seems to only change the recommended voltages (1.3V CPU is still "white"), which appear to be higher with it on)?
EDIT: EIST disabled. Does not sound like a function I like to use and does not seem to be overly compatible to OC'ing