What is the maximum amount of RAM that can be installed in a ProMagix x20 or x25 (C90S) notebook?

These system are configured stock with two modules, 1024MB each. You may physically install 4GB (two modules, 2048Mb each) but due to the limitation of 945GC chipset used in this notebook, 4GB of memory will only be recognized as 3GB. In some rare cases, 4GB (2x2048Mb) will not work at all in this notebook, so it is best to install one 1024Mb module, and one 2048Mb module. Dual channel support is not a concern.