TCCD refers to the actual IC's used in RAM. the IC's (Integrated Circuits) are the actual black chips on the RAM stick. TCCD are todays current best overclockers reaching high FSB's with little voltage. BH-5's used to be the best, and many argue still are, but to really get the most out of them requires over 3.2v generally which most people either can't do without a volt mod, or simply the fact it's not as safe to run that much voltage 24/7