[JohnR]

Originally Posted by macojoe

is it a possibility that if the mother board was week, that by pluging in the new memory in backwards or by being bad could have caused the mother board to fail completely??

You can't plug the memory in backwards as it is asymetrical in the pin layout - and if you did, you used more than a little force to do it

Pull the memory out and verfy that you are lining up the notch in the mem stick with the notch on the mem slot. When you push it in, if installed properly, the catches on each end of the memory slot should click and lock into the side notches ont the memory sticks. You probably have 4 memory slots, in which case try each stick individually in each slot. If still no go, use both 256 sticks and plug into the first two and see if it works, if it does not, try the next two slots, if it still does not work, put one in the first slot and one in the third slot. I don't believe that your memory needs to be installed in pairs