Aluminum cases don't really provide better cooling. It's only if aluminum is used as a heat transfer device -- like a HS -- that its higher heat coefficient comes into play. In the typical case, the only place this MAYBE has an effect is when the drive is mounted conventionally (secured tightly with screws). Do you think the difference vs steel would be more than a couple of degrees? (no) or that a change in position of the HDD to a higher/lower airflow spot would make a far bigger difference? (yes)
Your suspicion is dead on: aluminum cases are hyped -- mostly not by the case makers or sellers but by the buyers
, as far as I can tell. Case makers/sellers just choose not to enlighten. Why should they if it doesn't hurt anyone and helps generate more sales for more profitable goods?
Dynamat Extreme and similar products are NOT
sound absorption materials. They are panel dampeners
. They reduce panel vibrations. You can see why these sorts of products would be useful for improved audio in a car with its large areas (relatively) of unsupported sheet metal panels. See Ken's review of the similar Brown Bread
Sound absorption occurs with soft materials such a spongy acoustic foam, fiberglass, wool, etc. Materials such as these are designed specially to absorb sound - mostly -
They do block sound somewhat and damp panels as well, depending on density, adhesion, etc but those are generally more secondary functions.
I am working on a comparative review of the these products right now; look for that in a week or two.
IMO, aluminum actually does make a noisier case -- in theory. This is especially true with the very thin-paneled cases being produced. The heavier steel panel cases do have intrinsically better damped qualities -- that is, they benefit less from dampeners such as Dynamat or Brown Bread. But if you can reduce the noises at their source, the type of case makes very little difference.
>> Added: Differences in the material are, in practical terms, so much less significant than those in design and execution. In other words, regardless of whether it's steel or aluminum, I think the better design
will cool and quiet better.