> I’m trying to add memory to my iMac. I had one computer loaded with > 2 of the 1GB cards. I replaced one of them with a 2GB card, thinking > I would now have 3GB of memory. But now the computer info says I > have one bank with 2GB card and one bank “empty”. Do the memory > cards need to be the same size? They don’t *have* to be the same size, but newer Macs with Intel Core 2 Duo processors (or older dual-proc G5s) prefer it. But if one stick isn’t registering, it’s either in wrong or the wrong kind of memory. Try shutting down and reseating the RAM. The easiest place for Mac owners to go is http://crucial.com. Download Crucial’s little, easy system scanner, and let it tell you what to order. Their RAM is reliable and a fine value.