Power supplies for desktop computers are a standard design, but vary in output power. If you have more powered components - hard drives, optical drives, graphics cards etc. in your machine you'll need a larger power supply. This is the main consideration when upgrading your computer.
Power supplies for laptop computers are usually specific to that make of laptop with each one potentially having a different output rating and connector. If you need to replace your power supply you need to make sure you get one that's compatible:
- charging laptop with a different manufacturer's charger
- Will my new laptop AC power adapter work with my laptop, given these specs?
- ups (uninterruptible power supply)