That motherboard only has a 6 power phase setup. The VRM phases (the modules to the north of your CPU) are responsible for converting the voltage from your power supply into something your CPU and RAM can handle. The more phases, the more the power current is distributed over surface area and less heat is produced. The less heat, the less chance of running into issues when bumping of voltages.
That does not mean you can't overclock. You just have to be more mindful of the voltage you push into your CPU. My advice is to overclock as much as possible without adding voltage. When you hit the limit, increase the voltage very slightly and try again.
Every time you make a voltage adjustment, check the VRM phases with your finger, if they're burning hot, it's time to reduce the voltage. Luckily the 7700k is only 91 watt TDP, so you have room to work with.
While liquid cooling is a good option to reduce core temperatures, it completely strips all airflow from the VRM's. I would make sure you have airflow over them. In my old builds I would zip-tie a CPU fan over my phases for extra cooling. You can get creative and do the same thing.
Good luck friend.