Thanks for the answer, well someone swapped my 1600 4gb to a 1333 4gb. But when I put the ram in place along with the 2gb 1600 that I previously own that I said was working, it turned on but in my bios cannot read the 1333 4gb, instead it can only read the 2gb 1600. I tried putting on just the 4gb 1333, but my system turns off and on. BTW the 4gb 1333 works in my other systems.