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#21
Antec cases are typically "moderately" quiet. The 4890 is moderately loud -- not as loud as its nVidia counterpart. Hard drive noise is relatively insignificant when you are talking about only one or two drives.
Even with the 4890, your system will probably be somewhat quieter than my behemoth.
It will also somewhat depend on your choice of power supply. I have the PCP&C "silencer" 750, which is unusually quiet for so large a PSU. The 750-watt, single-12-volt-rail Corsair is less quiet, but not bad. Noise on power supplies varies greatly.