Each server add's to the total capacity of points you can save up to, so it's kind of two different things you look at - The point gain per tick, and the number of skill points you can store. I think each I500 server allows you to save up to 200 skill points,and generates 20 per tick. So if you have 4, you can save up to 800 Skill points. Typicly I end up with massive rooms of Skill servers to be able to boost skills on T4 and 5 androids, since the higher the android Tier, the more points per skill you need to spend. T5's are something like 1800 Skill points per 1 point of skill upgrade - it will tell you how many SP's are needed per upgrade for the selected android on the bottom of the skill widget.