All processors get extremely hot when the CPU fan is switched off, and you will find the Northbridge reaching almost 70°C - even more than that if you measure the temperature on the processor heat sink. We simply ran the test systems laying flat on the test bench table, which doesn't provide any airflow at all. We used the stock coolers and disconnected the CPU fan as we started the individual benchmarks.
The only system configuration that could actually finish PCMark 05 without a working processor cooler was the Pentium Dual Core E2160. Every other processor, whether AMD or Intel, shut down the system after only a few minutes. The temperature we measured at around the CPU heat sink exceeded 70°C.
Even the CPU benchmark, which puts every processor to work rather intensively, finished on the Pentium Dual Core E2160, though at clearly reduced performance (3375 instead of 4658 points). Obviously, the Thermal Monitor feature was working well, shutting off the processor when it was about to overheat. The reason that the Core 2 Duo E6850 didn't finish is probably its much higher clock speed level (FSB1333 and 3.0 GHz as opposed to FSB8000 and 1.8 GHz) combined with the quadrupled L2 cache size of 4 MB (instead of 1 MB).
We received the same results with the memory benchmark of PCMark 05.