Quiet computing used to be an underground hobby for people fed up with whining fans, buzzing monitors, and screaming hard drive platters. Thankfully, quiet computing has now become a mainstream selling point for modern computers. Witness the latest Dell Dimension 5100 and 9100 series PCs, with "quiet performance" listed as a main feature.
Recently, I purchased a Seagate Barracuda 80GB hard drive (the ST380011A). The Barracudas are well-known to be quiet drives, and I'm really impressed with mine. The noise level of this drive is so low that I can't measure it with my sound pressure meter. The only noise I can hear is the subtle chatter of the drive heads, and that can be mitigated with a Silent Drive enclosure, if desired.
Power Supplies can be extremely noisy. I was once fooled by an Enermax advertisement for their supposedly "Silent" power supply. The fans in that thing roar at over 35db. I replaced it with a totally silent Nexus PS, which is rated at <20db. Like the Seagate drive, the fan noise is not measurable with my sound pressure meter.
For CPU and Video Card cooling, I avoid fans altogether and buy Zalman heat sinks. Zalman makes heat sinks and heat pipe coolers for most mainstream CPUs and video cards. While they can make your hardware run a bit hotter than normal, the temperatures are well within rated operating levels.
I've had good experiences buying quiet components from http://www.endpcnoise.com and http://www.siliconacoustics.com/, but quiet computing has become so popular that I've even seen Zalman components at major retailers like CompUSA.
Did you know that persistent noise in a working environment is a known cause of stress?
