|"If this board is about linguistics (for instance, what "brand new" means), please let me know"|
No, the forum isn't about "linguistics", but "brand new" & over a year old are two completely different things. And since you said it was "brand new", I made the assumption that the CPU was recently installed & the overheating *might* be the result of an improperly installed HSF. Had you been more clear to begin with, we could be concentrating on what may be the cause of your problem rather than debating what "brand new" means.
Also, in your OP, you neglected to mentioned that you recently "put a different hd".
It seems to me that since the "comp was never opened (case) until a week ago" & was "used intensivelly for the past year (it was bought on June 2005), w/o no problems" prior to being opened, that the problem is probably related to the installation of the "different hd"...don't you think?
Now how about providing details about the HDD installation. Is the drive "brand new"? What is it being used for...storage or the operating system? If it's a storage drive, was it put on the primary or 2ndary channel? Was it installed in such a way that it might create excess heat within the case (i.e. too close to the existing HDD)? Is it possible that you inadvertently disturbed the CPU's HSF when you installed the HDD?
I suggest you take 02coled's advice...remove the HSF, thoroughly clean the old paste/pad from the top of the CPU & the bottom of the heatsink, apply a fresh layer of paste, & reinstall it.