Hi. This is my first post. I've owned a G5 1.6GHz PowerMac used since 2005. It came equipped with 256MB RAM (2x128MB PC2700 DDR 333 CL2.5v). Shortly after I purchased an additional 512MB RAM (2x256MB Kingston G5400 PC3200 CL2.6v), which has worked perfectly ever since. I have just purchased an additional 1GB of RAM (2x512MB Kingston G5400 PC3200 CL2.6v) to replace the 2x128MB strips, thus increasing my total RAM from 768MB to 1.5GB. I installed it today and was puzzled to find the System Profiler is displaying 4x256MB instead of 2x512MB and 2x256MB. In other words it is recognising the new RAM but only 50% of its capacity. Is this a common problem, and is there a remedy available? Thanks in advance for any comments.