Well silent is all relative
my main rig went from a vacuum quality sound to now the only noise is the SCSI drive love and the powerful 460watt PSU fan (the NMB 460 watt Thunder K7 specific PSU = lotsa heat)
Going to write up a small article about this but the short of it is, with the Tbreds I got an increase in speed, and lower heat output, which let me run some quiet gear. Went down to KDC and bought a load of cooling gear just for this today. Watch for the write up to happen sometime next week.
Quietness is good, now all I need to do is replace the one SCSI drive that makes the noise ( I have 3 of them in this rig and the other 2 Quantums are silent. the IBM 10k RPM drive is a loud mofo).
Its not silent, but its no louder than most small stock Dell or IBM workstations. and its a Dual 1.73Ghz AMD W/ 1Gb ram and a 100GB of U160 10k and 15k RPM SCSI love