RDRAM must be installed in matched pairs from same mfg. But be prepared ...relative to other types of RAM...it's very very expensive.
Try the links below:
You can either look for RAM by type brand and speed
You can have the Crucial diagnositc SW scan your PC and tell you what to install or go into the sites above and put your PC make, series and model number and it will tell you what the options are.
PS..It helps if you list the make, series and model number of your PC
I currently have (2)Toshiba, PC800, 64MB Rambus chips installed. I am interested in installing additional memory into my system. I've heard that it would be best to install memory from the same manufacturer/brand as what I already have installed. To avoid any technical mishaps or problems, should I also match the same model and serial# from what I already have? In other words, just how close a match should my new Rambus chips be compared to what is already installed to avoid any issues?