Zalman GT1000. I have had a few cases including Lian Li V2000, PC 25B, Silverstone TJ05 (worse case I have had by a country mile) TJ09 (rattling panels) and some of the old Coolermasters. The Zalman GT1000 is a country mile better when it comes to build quality and silence.
Bang on. For the money a great and very quiet case!Lian-Li PC-S80
The OP asked about quietest case and not what you can fit in it. I have 6 hard drives in mine using one adaptor and why do you need an over sized psu. I have a corsair psu, passive graphics and a scythe ninja with Noctua fan cooling the cpu and its quieter than my laptop. The thickness of every aluminium panel is what makes this case different than any other case. My Lian Li PC-25 is quiet but the GT1000 is nigh on silent.
Well, we just have to agree to disagree then. The Zalman is too expensive for what it is and the Lian Li I suggested is quieter. Noise-dampening front-door, a back-'hood' to quieten the rear 120mm fan, HDD's can be passively cooled. It's unbeatable for the price. Plus the Lian Li has thickened aluminum too.