Hi, We have a Dual 867MHz G4 (MDD) which currently has 1.75Gb RAM, and we were hoping to upgrade it to 2Gb. Currently, according to Apple System Profiler, Slot 0 (nearest the processors) has a 256Mb chip in it, slots 1, 2 and 3 (3 nearest graphics card) have 512Mb chips in them. This was confirmed with a "visual inspection" (well, more taking the 256Mb chip out and reading the label on it) We ordered a 512Mb Integral chip (PC2100, DDR, 184pins, etc, etc, etc) from Computer Warehouse - a respectable company who we've ordered many comptuers and software from before. On installing the chip, there was no label on it saying how "big" it was - this was the same as the three 512's already in the G4. We installed it in slot 0 - occupied by the 256Mb chip. We checked the new chip was seated properly and started the G4 up. The Apple System profiler said there was still 1.75Gb of RAM in - exactly the same as before. And, slot 0 was still filled with a 256Mb chip. I then put the supposed 512Mb chip into bay 3 (putting the old 512Mb aside) and left bay 0 empty. Booting up again showed that bay 0 was empty and bay 3 had a 256Mb chip in it. We phoned Computer Warehouse up, and they checked the number on a sticker on the new chip of RAM (a production code, which matched one of the other 512Mb chips....) and they confirmed it was a 512Mb chip... Very strange, since out faithful mac though otherwise... Anyone have any ideas why a company and a computer can disagree on how big a stick of RAM is? After checking on the CW website, they don't even list a 184pin 256Mb chip of RAM by Integral. Who should we believe? A computer (albeit a mac!) or a human reading data off a Mac (at the other end of a phone)?