In contrast to overclocking, you may prefer to silence your computer. Some high-performance PCs are very loud indeed, and it is possible to reduce the
noise dramatically. The main sources of noise are: Fans (CPU, case, power
supply, motherboard, Graphics card), and Hard disks. While total silence in
a PC is possible, it is far cheaper and easier to aim for something ’virtually
inaudible’.

Note that quieter computers sometimes run slightly hotter—especially in
small form factor (SFF) systems, so you need to monitor carefully what you
do. Usually you can’t overclock and silence at the same time (although it is
possible with the right CPU and cooling techniques). Sometimes CPUs are
underclocked and fans are undervolted to achieve greater silence at the expense
of performance.

Designing a powerful and quiet machine requires careful consideration in
selecting components, but need not be much more expensive than a normal, loud
PC. If you are looking to quiet an existing PC, find the offending component
that produces the loudest or most irritating noise to replace first, and work
down from there.