NAS type cases:
The most silent case has passive heatpipe cooling solutions, but 4 HDDs might be the loudest component:
HFX PowerNAS 5 HDDs in hot swap, one slimline optical drive. The CPU heatpipe cooler is
sold seperately. A
Pico PSU type set will be another ~100€ (
considerably less from the UK). The solution will run you ~400€ (350€).
The
Chenbro ES34169 has 4 hot swap bays for HDDs, a card reader and room for one slim optical and one 2.5" drive internally. There are two versions with 120W and 180W passively cooled PSUs.
The CFI A7879 has 4 hot swap bays, a 200w internal PSU, but no room for an optical drive. You can get it for
130€ or
£83.
The [url=Fractal Design Array R2]Fractal Design Array R2[/url] (
spcr review) has room for 6 3.5" drives internally, comes with a 300w PSU but has no room for an optical drive, not even front USB ports. It's prone to rattling.
HTPC type cases for 4+ HDDs The Silverstone LC 17 and LC20 along with some others can hold up to 6 HDDs.
Cubes for 4+ HDDs and a stadard PSUThe Lian Li Q25 has hot swap bays, but no rom for an optical drive. The V354 and Xigmatek Gigas have room for micro ATX boards.