Originally Posted by DuckieHo
What does a motherboard have to do with the physical size of a CPU?
The physical size of a CPU die is primarily a function of number of transistors and lithography process.
8 Core Bulldozer on a 32nm with ~2B transistors is 315mm^2.
4 Core Sandy Bridge on a 32nm with 995M transistors is 216mm^2.
Perhaps he meant the socket would have to be revised? Even then, the package
could remain the same, even if the CPU on it were physically smaller.
Less than 10% of the size and weight of the "CPU" is the actual processor, most is the IHS, followed by the PCB providing the connections between the processor and motherboard, then (typically) power circuitry and they top it off with an itty bitty hunk of silicon, only the surface layer of which is actually printed with the CPU.