the cores are exactly the same actully, just chery picked of sorts cause they drop the voltage on them to somthing really stupid like 1.1 volts which is just enough for the 400mhz. memory is ddr2, and usually tops out around 980mhz, but if you do some voltage mods who knows what you will get. with good cooling, people were getting their cores up to 1.8volts and stupid high clocks. of course the memory doesnt seem to wanna play nice with that kinda ocing.