I think "casefancase" would be strong for absolurely highest airflow...
http://www.overclockersclub.com/gallery/cases/789-pete.html
But not so great for sound level...
What kind components are you putting into it?
And for any chance to contain any noise case has to avoid having direct noise escape paths especially towards user.
Meaning silencing friendly case doesn't have any of those fancy grills/meshes making you see inside of case through front or side.
Another thing is that metal conducts vibrations well.
And thin metal sheets also start easily vibrating amplifying sounds.
Countering that needs either more rigid/thicker construction of panels or mass damping.
Antec uses the former in multilayer side panel design with plastic layer adding rigidity without weight penalty from similar thickness metal.
Mass damping again works by attaching some dense more elastic material like bitumen layer to metal panel, which effectively "sucks away" vibrations instead of allowing them proceed.
Both also make panels more opaque for sound waves trying to escape from case through panels.
Acrylic windows are also acoustically lot better material than thin metal sheet.
Because of its lightness at default acoustically way worser than steel aluminum case actually becomes acoustically lot better than still notably heavier undamped steel case after mass damping.
That mass damping just is definite requirement in aluminum case.
Myself went for aluminum Lian Li full tower in 2008 not because of its lighter weight, but because no other case had similar features/space while being silencing friendly.
going to be installing an arctic accelero extreme IV onto my GPU and that thing is big and heavy so sagging and strain on the PCI-e slot shouldn't be an issue
Actually for very long or complex shape heat pipes "hanging" position isn't the best possible.
After condensing to liquid and releasing heat liquid has to struggle up inside heat pipe for bigger distance against mavity.
Also with lots of heatsink bigger distance below heat source "heat" doesn't want to travel there as easily.
(heat/evaporated liquid wants to rise, liquid wants to fall down with mavity)
http://www.overclock.net/t/900251/gpu-coolers-that-actually-work-in-90-rotation-ft02-rv02
Question 1 in Q&A actually officially acknowledges that:
http://www.silverstonetek.com/product.php?pid=242