do you got lots of ide,pci,isa, and so on things that are using the cpu's power?...
and/or in windows do you got alot of things running like loads and loads of programes?
and when cooling your system.. do you got hdd cooling fan sets?
and have you tryed a different cpu? if you have one around!
oh and try running the system without the side on the case... go into the bios and see if the temp has dropped?
good luck mate
<font color=red>im a boring old fart and a drunkin bum. </font color=red>