[Oli]

Please remember the thermal diode of most E8x00 models is faulty. It delivers false values to real temp / core temp / BIOS. Most of the time those diodes report temps that are way too high but it could also be the other way around in your case.

I was surprised as 17 is very low (must be quite cool in this room) cause with even a very very good cooler the cpu should idle some degrees above the room temps.

With 21/22 in the room my Mugen cools the E6700 down to 30 degrees. The E8400 stays much cooler than E6x00 so I'd guess idle temps should be around 5 degrees above environment temps.