24" Aluminum iMac, 2.4GHz core 2 duo, mid-2007 model. I purchased 2 2GB SODIMMs of pc5300 DDR2 RAM to upgrade. I inserted them into my iMac and got the black screen, no beep symptom. I put the original RAM back in, and it boots normally. I tried both of my new SODIMMs in both slots, together with each other, individually, and mixed with the original RAM, and it will not boot. Here's the twist. I put one of the new SODIMMs into my Dell Latitude D630, and it works just fine. I believe the RAM meets all of Apple's requirements. Any ideas what I could try next? Thanks!