On Server Fault, we were discussing this question in chat. There are non-native speakers in the chat and somehow we got on the topic of grammar and proper use of commas.
The sentence of interest:
I have just got a new Ubuntu LAMP VPS server, which I am trying to configure.
Some people thought that the comma was superfluous. Others did not.
When is it appropriate for a comma to preceed the word which, and is the example sentence above correct?
Also, before you vote to close this question as a dupe of this, please consider the differences between the two questions and ignore the similarity of the titles. The OP's example sentence was restructured in that question instead of addressing the proper use of commas.