2,000RPM is just a bit above the threshold I'd recommend for near silence... for a 120mm fan I'd look for 1,400-1,600RPM as the range, but everyone's hearing is a bit different (along with people's definition of what qualifies as silence!). However, these are sleeve bearing fans, so that will help somewhat.
Core i7 4770k 4.2Ghz
Crucial Ballistix Sport LP 1600MHz 32GB
EVGA GTX 480 HydroCopper FTW
ASUS Xonar DX
Corsair Neutron GTX 240GB | Windows 7 64-bit
Apogee XT + MCP655 & Thermochill Triple 140mm Radiator
Corsair AX1200 PSU | Cooler Master HAF-X