T61p Penryn temperature thresholds

I don't know. No such information are published by IBM/Lenovo.

Try running "stress -c <number of CPUs>" (this program just uses the CPU and so generates heat) when tpfand is disabled (i.e. "Control fan by software" is NOT checked) for about 1-2 hours and see how hot your notebook gets. It's a good guess that these temperatures are safe, because they can be achieved during usage of the notebook under normal circumstances (i.e. fan controlled by embedded controller).

I don't know. No such information are published by IBM/Lenovo.

Try running "stress -c <number of CPUs>" (this program just uses the CPU and so generates heat) when tpfand is disabled (i.e. "Control fan by software" is NOT checked) for about 1-2 hours and see how hot your notebook gets. It's a good guess that these temperatures are safe, because they can be achieved during usage of the notebook under normal circumstances (i.e. fan controlled by embedded controller).
FAQ #104: “Which temperatures can be considered as “safe”?".

Thanks for your response! Some temperatures do not change even if "stress" is is running for over an hour. How do I find out, which sensor number stands for which sensor?

Thanks in advance!

You can unplug the battery to find out which sensors belong to the battery.

CPU goes up very fast when you ran stress.
GPU can heat up when you run glxgears or another 3d-app.

But for the rest there is no easy way to find out without opening your notebook.