Look up mobo specs online, get the mobo designation from dell by looking at your computer specs on they website. Also look to see what DDR2 your mobo supports, if it doesn't support the newer 800 than get 667 (I think thats the number) or whatever it actually supports. Problem with moding pre-build PCs is that they are build to be as unfit for moding as possible, dell doesn't want you to upgrade your RAM, dell wants you to get a new PC from them with more RAM.A dell mobo
how do i tell what pinns i need