Sorry if I didn't give enough info. I have an ABIT motherboard that support up to 4 GB of RAM. running win98sec and at the moment I have 512MB of DDR RAM. I bought the RAM stick from a web site that according to the motherboard you have narrows the options to the best possible choice. Now, the problem is that there are three type of DDR available and I don't remember what the one I bought is. The only thing I know it is a DDR. The differences are minimal but there's £30 difference between the three: DDR PC2100 • CL=2.5 • Unbuffered • ECC • 7.5ns • 2.5V • 64Meg x 72 DDR PC2700 • CL=2.5 • Unbuffered • Non-parity • 6ns • 2.5V • 64Meg x 64 DDR PC2100 • CL=2.5 • Unbuffered • Non-parity • 7.5ns • 2.5V • 64Meg x 64 The one I have has to be one of the three 'cose I bought it from the same web site. The only thing I remember wasn't the most expensive (which is the first one listed above).