How to make your PC quiet
Run silent, run deep
PCs are becoming noisier. As components have become faster, the heat they generate has increased. Since that heat is traditionally dissipated using a variety of fans inside the case, the number and size of these fans has grown too, to the extend that they have become the major source of noise within a PC.
They are not the only source of noise. Hard disks have platters that spin at very high speeds these days, and optical drives like DVD and CD units generate noise too. Badly designed cases have side panels that vibrate.
If you're tired of the racket your PC is making, you have two choices before you. You can either go for a lower performance PC that will probably not provide all the latest features - or go for no compromise PC with all the latest and most powerful processor, graphics card and so on. Of course, the high performance PC will need a number of modifications to control the noise.
Small form factor PCs
A lower performance PC generates less heat and needs less cooling so you only need the minimum of fans - and possibly or no fans at all.
There are several manufacturers of small form factor (SFF), mini-ITX and other compact systems who integrate parts like the graphics chip onto the motherboard. While these machines are more than adequate for most tasks like word processing, browsing the internet, and even watching DVD movies they wouldn't be the first choice of an avid gamer and they wouldn't be up to the most demanding ray-tracing or video editing tasks.
These PCs also tend to use lower-end processors, and offer very limited scope for future upgrades. If the processor is built onto the motherboard, you may not be able to replace it at a later date. It's highly unlikely that you'll be able to upgrade the graphics card or add a PCI card like a modem, network or TV card, for example. They just don't have the space. If they do advertise a free PCI slot you may find that it's a 'low-height/low profile' slot that won't take a standard PCI card.
These machines tend not to support larger size RAM modules. You may also find that you'll have to make do with a single optical drive and won't have the luxury of both a DVD player and a CD-RW. Sure, you can have a DVD-/+RW that covers all the jobs of a standard DVD player and CD-RW but it will probably have to be a laptop-oriented 'slimline' unit. If a new and faster optical drive is launched it will ship in standard size for desktop PCs first and it may be months before a slimline version follows.
The upside to having one of these machines is that they tend to look good, occupy very little space and can be squeezed into your music cabinet between the VCR and the stereo. You can also get them in silver/black and in matt/gloss finish to match most hi-fi equipment. And they make little or no noise. Do a search on the Internet for terms like mini-ITX and you should find links to some of these systems.