You're welcome :)  I tried locating some more specific information about what the X-Cool jumper actually does.  Enabling it allows temperatures below -50*C (roughly) to be more accurately reported.  If you enable the X-Cool jumper with regular air-cooling, then you might experience problems with the CPU temp display being stuck at some high innacurate value.
 
Beyond correctly reporting lower temperatures, I'm not sure if it does anything else (like changing resistance/impedance) and/or if it opens up a larger range of possible CPU/VTT voltages in the BIOS on some boards, but I couldn't find any info beyond that.