If its showing in the POST screen then it wont be the CPU, if you reset the BIOS then it all goes back to default, RAM speeds, fans at full speed etc as none of the cool n quiet technology will be enabled (as you have reset the BIOS you will have to redo any custom settings like this)
Make sure that the HDD is listed in the BIOS as the 1st boot device and disable the 2nd,3rd,4th options etc.
Let us know how you get on