Tivo Premiere - High Pitch Noise from Board

I purchased a used Tivo Premiere, when when it is plugged in I can hear a high pitch hum coming from the inside the unit. It is not loud enough to bother us when watching TV, but it is noticeable when the TV is off and the Tivo is idle.

It is not coming from the fan or the hard drive as I swapped both of these pieces with the same hardware of another used Tivo Premiere to troubleshoot the issue. I do not see any other moving parts that I could easily swap to diagnose the issue.

Has anyone else run into this issue before? Could it be fixable?

Thanks!