AMDHero :
i was thinking of buying R4 but the sound proof padding put me off as it stores more heat
I've worked with silent cases, including the R4, quite a bit, and they're my second favorite. (Behind small form factor cases, which are kinda my thing.) They're ideal if you're watercooling. There's nothing better.
That being said, however, heat isn't an issue even if you're air cooling
as long as you use graphics cards that don't dump heat back into the case.