What is the quietest APU unit?

I'm curious, could you please explain what the quietest APU (Accelerated Processing Unit) unit currently available on the market is? I'm specifically looking for a unit that runs with minimal noise disruption, as I intend to use it in a quiet work environment. Additionally, if possible, could you provide some key features or specifications that make this APU unit stand out in terms of its silent operation? I appreciate your insights and expertise in this field.