more specific..?? ddr 2100 is ddr that runs at 266 or it will take as fast as you can put in it or they make as in pc3500 but you cannot use it. The 2100+ is an xp chip stock clocked at 1733mhz and the chip will oc to 1911 stable with the right setup. Also the 2100+ is a tbred with agoia stepping "good chip" anything else..?