My new Quicksilver Mac says in the System Profiler that the bus is 133 megahertz, so is the RAM. It shows three slots, but one of them says it is empty, eventhough it has a ram card in it. I tried a couple of different ram cards in that slot, none of them show up in System Profiler. I haven't yet tried one from a working slot. I did find that one of the ram cards is 512 megs, the others are 256 megs. They all say 133 megahertz, if they say anything. So, at least I have 768 megs of working ram. The third slot may be bad. Thanks for that serial number site. -Don