Hello, I have chosen to post this question here because over the years I've found a lot of great tips that have helped me solve numerous problems on my own and other Macs that I have repaired. A tip of the hat to you all. I am on the path to installing Leopard on my G4 733 Quicksilver. Step one, based on all the searches and reading I have done to this point indicate to max out the ram to 1.5 GB. I bought the machine with 512 MB. Other than replacing the HDD's and adding an Airport card (cost me a buck at Free Geek in Portland) not too long ago, the machine is as shipped. I purchased 3 512 MB DIMMs but when I put in all three, the video output fails. All 3 DIMMs are good, as you can use any two of the three along with one of the old 256 MB DIMMs (which must be in the first slot) and get 1.25 GB. Even if I use just one of the new 512's in the first slot, it will prevent the video card from working. The OEM video card is a 065-2581 NVIDIA GeForce2 MX - 32MB SDRAM. The first slot (Slot 0?) I am referencing is the one closest to the CPU. Thanks for your input in advance.