Ryzen 7 is a powerful CPU, and it can benefit from a 240mm AIO cooler. The main reason to get a 240mm AIO is for the increased cooling capacity. If you want to push your Ryzen 7 to its limits, then a 240mm AIO will help keep things cool. If you don't plan on pushing your CPU too hard, then a 120mm or 140mm AIO should be fine.