My old ram is 2x Vengeance 8gb 3000mhz my new ram is 2x G.skill 8gb 3200mhz when I installed the new ram with my old ram in my pc turns on fans running but my keyboard/mouse/monitor show no sign of life. Now with only the Vengeance in it works but also with only the G.skill it works but together it doesn't... So right now I'm only using the G.skill since it has 3200mhz over 3000mhz