A:Answer Hello, thanks for asking this question! It's normal for the transformer (used to power the clock) to emit a slight humming sound when the microwave is plugged in, but not in operation - though this noise is usually not noticed. If you're looking to replace your current microwave, we're seeing that Model #PEM31SFSS (this microwave) is comparable in size, capacity, and microwave watts. Additionally, if you're interested in a built-in trim kit for this model, here are those kit model #s - 27" Trim Kit: #JX827SFSS and 30" Trim Kit: #JX830SFS. Or, the undercabinet hanging kit for this model is #JXA019K. We hope this helps! All the best, Kelsey@GEA