Roberto Safora Romay queries: "What those 83 Mhz mean' The "83 Mhz" means 83 megahertz., it is a speed indicator. Roberto also asks: "Which are the elementary things to watch when it comes to mix extension chips on video cards?" I don't know about video cards, but with RAM, the memory SIMMS need to be the same size and speed within a memory bank to work. If you have mixed and matched, you are probably running into the same problem. --Sam Smilie