I have been trying to upgrade the memory in my computer and have not been successful. The computer I have is http://h20564.www2.hp.com/hpsc/swd/public/readIndex?sp4ts.oid=3658094 running windows 7 home premium 64 bit. It currently has 2GB RAM(4 cards). I had 4 1GB cards at the office that was removed from our server but was not able to get them to work. I got 4 other cards from the IT Company that does our office. They said they were used but confirmed as good working condition. I got the same results from both sets. When I turn on PC I get 5 beeps. According to the HP website this code is memory. I tried everything, doing just one at a time, 2 at a time, different slots, 2 of the old card 2 of the new one always with the same results. Every time I swap them I make sure they are pushed in far enough so that it closes the tabs. I updated the BIOS and reset the CMOS . I’m running out of idea. Anything else I can try? Or am just unlucky and have 8 faulty cards. Every time i put the old ones in it starts-up with no problem. These are the cards I'm using http://www.digchip.com/datasheets/parts/datasheet/301/MT18HTF12872AY-53EB1.php.