I have a mother board that can have DDR and SD memory you just have to change some jumperto switch between types my system originally came with pc133 256 sdram thne i ordered some 256 pc2100 ddr from crucial. then i noticed i would get more BSOD's they were actually memory dumps and then i woulld have to restart this would happen when i started certain programs such as my cd burning software or when iwould just serf the net. I was thinking maybe I got bad ram so i put the old SD ram back in and it was working fine after that. I was wondering if it was bad ram or if i was installing it wrong. My mother board's book siad I just have to change the voltage type and then change the ram selector jumpers. So if it bad ram do i just call crucial and tell them? I was also wondering if there is a program that tests to see if you are using bad ram? thx for any help anyone can give me