The power supply and the hard drive are two components that can most likely be swapped out while the server is still running, if they support hot swapping or hot plugging. Hot swapping or hot plugging means that the device can be added or removed without shutting down the system. The operating system automatically recognizes the changes that have been made. This feature is useful for minimizing downtime and improving availability. The CPU, the GPU, the cache, and the RAM are not hot swappable and require the system to be powered off before replacing them. References: https://www.geeksforgeeks.org/what-is-hot-swapping/https://www.howtogeek.com/268249/what-is-hot-swapping-and-what-devices-support-it/