e6600 stock hsf
x1900gt with cooler
speedfan opens with these temps, I haven't changed anything
SpeedFan's Aux temp has displayed erroneous values through several releases, which has been a concern to many for some time now. I emailed a few months ago for info regarding this issue, but never received a response, however, Aux appears to provide for future expansion of motherboard sensor inputs, such as RAM, PSU, or case temps. Since Aux is not connected (NC), it randomly toggles through possible display values. As this does not present a problem, I did as most do, which was to disable Aux, and disregard it.
As for the clarification of C2D temps, check out the following topic:Core 2 Duo Temperature Guide
Hope this helps. 8)