I utilized a memory upgrade website and it recommended 1600mhz memory upgrades (2) 4gb sticks of DDR 3 for my Dell 1564 Inspiron laptop. After installation I got the blue screen and windows shut down. I reinstalled my old stock memory of (1) 2gb and (1) 1gb stick and it runs again. After a little research from Dell utilizing my service tag my laptop is designed for 1333mhz memory up to 8gb (2-4gb sticks). The memory I purchased was 1600mhz based on the recommendations of the site. I actually checked several sites and they all recommended the same thing........1600mhz DDR-3, (2) 4gb sticks. Suggestions? Thanks, Byron