If so, the lack of address lines to the memory slots and how the BX chipset boards uses two CAS lines to get 256M of memory in a slot AKA "double-sided" makes the common off the shelf memory show up as 128 megabytes.
Crucial.com usually gets it right and supplies the proper sticks and tells you how much of what type you can put in the machines.
Or you read the motherboard manual.
I have 3 computers, one of which I built and they all take PC100 memory. I recently bought a piece of 256 and it didn't work. I tried to put it in another machine and it didn't work there. I switched those 2 machines memory and found they were not interchangeable? I had no idea that there were different kinds of memory within one type? How do I find out what kind I need?