Tray noise!

I have a very non-technical question.

I have 3 lower-end/home QNAP boxes: a TS-431, a 431P2, and a new 664 which is allowing me to replace / age out an old ReadyNAS.

All the NASs have WD or HGST drives, which are not silent, particularly when the heads seek. But they’ve been indestructible for me so far.

What gets me is the vibrations in the NASs themselves, like trays in the slots, seams along the case. Even the 664 has a sliding cover that seems to buzz a little. The drives are firmly screwed to the trays, and the trays are firmly latched to the SATA connectors in the boxes. They’re all sitting on flat and solid surfaces next to my desk.

I’ve tried tape, little rubber shims, a thin foam mat, more tape, and these things have been buzzing away, on and off, for years. Any ideas before I lose my mind completely?

Note: the 13-year old ReadyNAS 104 that I’m replacing (and is going to a relative) still runs like a champ with its 13-year old HGSTs, but, more importantly, has never made case noise.

Appreciate any advice. I’m not super technical and have learned a lot here.