Interesting, which noises does the hgst make? Asking because the noises I had issues with didn't seem like vibrations of the drive itself or it hitting any metal. It was clicks from the drive head parking or something like that, which is a feature on newer, particularly larger hard drives from what I understand, I don't think thicker rubber would really have any impact on the sound itself tbh

As someone with both a Fractal Design Define 7XL with 9 drives in it and a mini version of the case with no drives, I can say the following.

1. You don't want any transparent panels, the solid ones dampen noise with the padding on them.

2. The noise dampening is perfect for low speed case fans or cooling fans.

3. The noise dampening will not stop the following

a) Fan stop and start sounds (in my case a pesky GPU that needed the fans on nonstop at slow speed because they rattled starting and stopping)

b) hard drive noises, it can reduce the whine, but the head parking sounds are inescapable in my experience thus far. However I am certain this will depend on the drives you have. Prior to having this case and internal drives, I had 9-10 external drives plugged in via USB, and those drives were inaudible for the most part without any noise dampening besides being under a table that had a cloth over top of it.

So if you need silent, you probably want 5400rpm drives that can spin down when not in use, or drives that don't make loud head parking sounds the way current larger/enterprise drives do.

Now as for other options to dampen noise further, I tried the following.

1. Surrounding the case with noise dampening panels. This didn't work and resulted in heat buildup.

2. Putting the case inside a shoe cabinet, this made the noise echo.

3. Putting the case inside the shoe cabinet with noise dampening panels outside. This worked for noise but heat buildup was a problem, so it wasn't viable.

4. Giving up and moving the server into a closet. This was the only thing that really made it inaudible, allowed me to run the fans faster, and didn't cause heatup issues, though the closet does get warmer than the room around it.