My WW cooled rig (see sig) runs 57C loaded by cpuburn.
more details here:
http://forums.procooling.com/vbb/sho...&threadid=7420
I can't say I trust this diode, but I did make sure to bend it upwards to touch the back of the cpu, and to coat it with thermal paste. If I could find a thin enough diode to put on my electronic thermometer, I would put it under the block next to the core.