motherboard is from intel hp company 304bhMake and model of the motherboard is the most important thing to know.
THANKS MANI doubt you'll need to do a BIOS update as it looks like the i7-870 is one of the CPU options that was available for that computer.
it can help but depend what is your cost.THANKS MAN
on last question is it advisable to change cpu for the sake of performance??
i mean i have to replace CPU put thermal paste and thats it or are there some more steps