Most boards I've seen max out at 1866 or 2000 for the ram speed when overclocking, but it's not guaranteed. Depends on your skill level with bios settings and luck of the draw for the cpu. Some overclock well; others don't. Be sure to use a well branded power supply such as antec, corsair, ocz, seasonic, enermax, or xfx. The wattage depends on your total system load, especially the video cards.