User interface guidelines like from MS, Apple, Gnome etc give usually quite clear suggestions on this:
In addition you can use select box when you have to save space or default choices is usually good enough, so users seldom have to look at their choices.
Thirdly it can be used for days of week, months etc. That is things where you know what choices you have without being shown all of them. If I see "February" in a select box I can pretty much guess what all the other options will be.
Rational for why you use one GUI element over another
I general radio buttons are usually preferred because users can see all their choices right away. However showing all the choices can take up a lot of valuable space in the user interface. That is why most guidelines suggest using other methods of selecting when there are a lot of choices.
E.g. a scrollable list can show arbitrary number of choices without taking up a lot of space. The downside is that you can't see all the choices.
A select box is different in that we use it when showing the user all the choices are not that important. E.g. when the user can can guess the choices, or will very seldom need to change the default settings. The select box is primarily there to show the user what the setting is. However when there are lot of choices a select box can be awkward to navigate and thus a scrollable list would be preferable.