HD seek noises are one area where quiet case design helps lot.
HDD itself radiates noises so plain soft mounting isn't enough for making them really quiet, that's why damped panels with indirect noise escape paths are pretty much mandatory for really quiet PC. Same things also lower noise of graphic card and other noises created by components.
That's also why Antec P180 is so quiet even with higher end parts.
But Antec P180 is just cramped case with little device bays so it was out of my consideration when damped CM Stacker T01 with noise leaks in front started sounding too noisy. After something like three month active (+2 months less active) studying I ended up to A71 and although aluminum is acoustically worser than steel there just aren't any other cases with even closely as good combination of space, easy access to all components inside case and silencing friendly feature set.
Knowing that vibration problems when taking case out from packet weren't that big surprise and is probably common problem with aluminum cases. Little loosely attached top edges of side panels definitely don't help in that but after adding damping mat that rattling disappeared totally and mat also increased rigidity of panels.
Here's pic of it during building, shows well how efficiently design uses space for lot of device bays still leaving plenty of space for accessing everything.
HDD cage itself vibrates slightly (can be felt) but with generously damped case that slight vibration coming through rubber washers doesn't cause any noise and lack of direct noise escape path further dampens HDD/fan noises.
So despite of acoustically worser material aluminum case can be made very quiet and light weight actually turned to nice advantage: Case itself weights only ~9kg which rose to ~12kg with damping leaving final weight lot lower than similar size steel cases with even lacking features. Already aluminum sided Stacker weights 14kg (same as Antec P180) without anything and 16kg with damping and was still lot noisier because of acoustically bad design/features.
With that good results achieved from quiet design with damping I'm now preferring not to waste weight for heavier case and wouldn't even anymore think about getting steel case.
(also doors of Lian Lis can be changed to open in either direction)
And that piece of acoustically near useless Akasa mat is there only because I wanted to leave more air space around PSU, other mats are actual damping mat: that smoot dark mat is current BeQuiet Noise Absorber (BGZ14) while that piece below motherboard and smaller strips of it better visible in big picture are older 3mm thinner version of it.
I have just returned from a skiing holiday from Finland, Yllas. Fantastic country
Recent snow in UK probably now doesn't feel as such big deal.
Next time try northern Finland near christmas... you won't be bothered by sun because it doesn't rise at all...
(or at summer there'll be long wait if you wait for sunset to go sleeping)
