well that's not really enough information, but seeing how this is basically the 3rd question today where someone doesn't know what kind of RAM they can use I'm going to assume your older computer used SDRAM and you're trying to put it into a computer that uses DDR. All you gotta do is look at the RAM and the slots in the motherboard to find out if they'll fit. SDRAM has two notches you gotta line up while DDR only has one, slightly to the right of the middle. You could always use a program like CPU-Z to find out exactly what kind of RAM you are running.