As the CPU and Power Grid govern what you can put on your ship, the Capacitor dictates how often you can use modules and warping. Every ship has its own unique Capacitor attribute, just like CPU and Power Grid. It recharges on its own, and there are modules that can modify most aspects of the Capacitor. When you go to warp or use a piece of equipment (which we call ' modules' in this game), your Capacitor gets drained. Co-Processor modules can also give more CPU, in exchange for Low Slots. CPU fitting can also be improved with the various 'Upgrades' (Weapon Upgrades, Energy Grid Upgrades, etc) skills, which generally lower the CPU requirement for specific modules of that type.

Training levels in Electronics skill can increase available CPU. Reactor Control Unit, Power Diagnostic Unit and Micro Auxillary Power Core modules can also increase available power grid, at the expense of Low Slots. Training levels in the Engineering Skill can increase the available Power Grid in all ships a pilot owns. Every ship has its own CPU and Power Grid attribute, which can be modified with equipment. Even if something is not 'meant' to be used on a class of ship, with clever balancing and the right support equipment, it's still possible to bend the lines.

You might have room to mount a battleship-class canon, but you probably won't have the CPU or Power to pull it off. For now, these are the boundaries that you operate within when mounting things on a ship. You'll learn how to balance the two as you get more experience and decide what tools you like to use best. Some have more in one or the other, some are good and bad in both. Everything has a CPU and Power Grid requirement. Merely measure how much stuff you can use.

Eve fitting guide slots