Originally Posted by Speced
So basically Friend asked a question that I actually don't know. He asked if you overclock the CPU/NB, is that just the CPU or does it overclocking something on the motherboard aswell?
The CPU/NB is NOT on the motherboard, as most people think, in fact it is the memory controller on the CPU die, the IMC (integrated memory controller). It is known as the CPU/NB because this memory controller function used to be delegated to the northbridge chipset on the motherboard. Not exactly sure when, but this function was moved onto the CPU die a while ago. The name just stuck I guess. Now the northbridge on the motherboard controls things such as USB ports etc I believe. You get a performance boost from overclocking the CPU/NB because it lowers memory access times, making the system feel faster. The fact that it is on the die is also the reason you can raise the voltage up to that of the processor voltage. The ACTUAL northbridge (on the mobo) can only go up to like 1.2 volts. An example, on my Gigabyte 990FXA-UD3 motherboard, the official memory supported is 1866, however if you dont have a bulldozer proc,and say, a phenom II instead, then the maximum default speed is only 1333 mhz. This is due to the fact that the default/supported speeds are based on the IMC on the CPU die, and therefore change based on the CPU that is in the socket. Moving things onto the CPu die is the way the industry is going. Ivy bridge procs have the PCIE controller built into the die as well. This is why you see motherboards with PCIE 3.0 support, but they dont have the capability yet, as there are no ivy bridge procs to allow them to test it out. Soon, almost all of the motherboards functions will be right on the CPU die. Hell, even graphics chips are on the CPU die nowadays. Anyway, little off track there but I hope i answered you question!
EDIT: the ref clock is not anything you are overclocking really, it is just a setting that tells your components how fast to run. Kind of like changing your CPU multiplier to overclock. Think of it as setting the cruise control on your car, you are just simply telling the car the speed you want it to go. As above said, the ref clock affects many of speeds in the system as well.Edited by Shadow_Foxx - 2/19/12 at 10:42pm