A liquid cooled system can perform better because the processor is cooled by liquid, not air.
The heatsink is a bit more efficient, so the boards are less likely to warp due to excessive temperature difference on different regions of the boards.
You literally have a series of tubes in your computer.
It’s more expensive than air cooling.
There’s always a risk of a spill or condensation that could cause a short.
It’s not portable, it’s not easy to build, and it’s not easy to maintain.
