I have a Mid-2007 20 inch iMac that has been running on 2GB of memory since I bought it. Recently I decided to upgrade the memory, and purhased 2x 2GB PC2-5300 667MHZ DDR2 Sdram from Amazon, which I am 99% certain is what I required (Apple's website doesn't sell memory for my desktop anymore, but a few months ago this is what it told me I needed). Anyway, when I remove the 2x 1GB ram and replace it with the 2x 2GB ram, I hear the chime but there is no display whatsoever. So there are 3 possibilities in my mind: 1) what I purchased is faulty 2) I bought the wrong type of RAM 3) I'm an idiot and installed it wrong Option 3 is least likely, because while I AM an idiot sometimes, I installed it exactly the same as I removed it. If anyone has any ideas or suggestions, I'd love to hear them. Thanks, guys.