1. Improved cooling: A new computer case can provide better airflow, which can help keep your components cooler and extend their lifespan. With improved cooling, you may also be able to overclock your components for better performance.

2. Better cable management: A new case can provide better cable management options, making it easier to keep your cables organized and out of the way. This can improve airflow and make it easier to access your components if you need to make changes or upgrades in the future.

3. Aesthetics: Let's face it, a new computer case can make your PC look better. With many different styles and designs available, you can choose a case that matches your personal taste and style.

4. Quieter operation: A new computer case with improved cooling can also result in quieter operation, as your fans won't need to work as hard to keep your components cool. This can make a big difference if you use your PC in a quiet environment or if you're bothered by the noise of your current case.

Upgrading your motherboard, power supply, and cooler can potentially improve the lifespan of your PC in the following ways:

1. Better power delivery: A higher quality power supply can deliver cleaner and more stable power to your components, which can help prevent damage and extend their lifespan.

2. Improved cooling: A better cooler can help dissipate heat more efficiently, which can prevent overheating and extend the lifespan of your CPU and other components.

3. Better compatibility and upgradability: Upgrading your motherboard can allow you to use more powerful CPUs, GPUs, and other components, which can help keep your system up to date and extend its lifespan.

That being said, upgrading your PC components alone does not necessarily guarantee a longer lifespan. It's important to also take good care of your PC, such as regularly cleaning it of dust and debris, properly configuring your software and hardware settings, and avoiding overclocking beyond safe limits.