Sounds like you've got something wrong in there... Three possibilities.
1) You've got the heat sink mounted improperly. Remove and check it for proper contact. You can do that with thermal paste. Remove the pre-installed heat pad if you haven't already, clean the CPU and HSF, then put a small amount of heat paste on just the processor, install the HSF, then remove it and look at the HSF to see if you have a good contact patch.
2) You may have way too much voltage going into the CPU. Check your BIOS and make sure you have it set properly. If you're running an Athlon Palomino, you should use 1.75 volts. If you have a T-bred XP1700+, then use 1.5 volts. A good way to do this if you're unsure about how to set it up is go into the BIOS and simply select "Setup Defaults" and that should default everything automatically.
3) The temperature monitoring itself may just be messed up. Have you checked these temperatures in the BIOS "PC Health" section, or are you using other software? Check the BIOS monitoring to see what that says. Sometimes these temps are off a bit, but not usually to the extent that you are experiencing. You might try a BIOS flash to see if that helps with inaccurate temperatures.
Good Luck.
Scout
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