Has anyone tried to upgrade the 4GB of standard memory in the RX4100?
This is not officially supported.
Some users have already tried alternative options with another model the DX4000 on the following link:
http://community.wd.com/t5/WD-Sentinel-Products/Adding-RAM-on-a-Sentinel-DX4000/td-p/473640
The maximum RAM that the ATOM supports is 4GB.