At the time of custom requirements such as bandwidth upgrades, RAM upgrades etc. A solution is prepared which is most feasible by the client or normally a client upgrades his hosting package to a higher configuration or server specifications.
With a dedicated server, it all depends upon the hardware chassis support. For e.g. we cannot add 4 drives to a basic P4 configuration as the hardware chassis does not support it. In this case, the only option is to upgrade to a dual core configuration.
Regards,
Shane Phillips