Acer specs? Original(1) replacement(2)

Hi, Would I be somewhat naive to believe that the User manual ( for any model ) specs could be taken as gospel ?
My laptop has User manual specs which state clearly that a particular CPU(2) will work, along with several others.
I was given a slightly higher CPU(2) which was mentioned in the manual specs. After installing and booting it was recognised correctly in the BIOS. It ran beautifully for 30 minutes or so at which time I decided to reboot.
BIOS progress bar finished and a Black screen with a flashing cursor appeared and then both fans went into overdrive. Nothing else happened, just a Black screen and screaming fans.
I removed the CPU(2) and replaced it with the original(1), booted and everything was back to normal, rebooted(1), as per normal.
Exchanged to CPU(2) and got a Black screen and screaming fans.
At this point I turned the comp off and left it for an hour, I then turned it on and all went well. After running for 20 minutes rebooted and got a repeat of the above.
The only difference is that CPU(2) has Thermal Sensor 2 . I have checked all of the Intel processors of this rating and they all have it.
I have deliberately not mentioned the particular CPU as I don't want people side tracking and asking, why bother for such a small uplift in rating etc!

 

Is the new CPU a 45nm one, replacing a 65nm original? In that case, you will probably need to update your BIOS.