I have had a bit of trouble installing some additional memory into my PC. At the moment I have 1536 MB of RAM installed, a 1GB module and a 512MB module. I bought one more 1GB module, the exact same model as the 1GB module I currently have installed. When I replace the 512MB module (I only have 2 slots) and head into the BIOS, it only recognizes the new module, the other memory bank showing as "None installed".
I have tried many configurations and I cannot figure out why this happens. They are the same exact model, after all.
OS: Windows XP SP3
GPU: Nvidia GeForce 8400GS