My system has 3.8 GB of ram. My system allows 8 GB of ram. If I insert another memory chip of 4 GB, do I have to make any other changes in OS setting etc?
No, you do not have to make any system changes.
If possible, select a model from the same vendor.
Some of the important RAM specifications are:
Additional information about the usage of swap:
Swap may be used for high-memory-intensive tasks such as extensive editing of large videos.