Itronix

I purchased ram (used) for my CPx J650GT and it doesn't work. All the laptop does after the ram is in is power on, but won't boot and then turns off. I can hear the disk drive move when trying it. Sometimes it will power on (can hear the harddrive), but nothing appears on the screen and it won't do anything, so it shuts itself off. It was stupid to buy used ram, I know, but if it was bad, wouldn't the laptop tell me that it has memory failure? I read that the not booting thing when installing ram can mean that it is not installed properly, but it seems to be. So, basically can anyone guess if the memory is bad, or if it is just not compatable with this laptop? Thanks.