Device controllers, also known as device drivers or simply drivers are a set of small applications that are added to the operating system's core that makes it capable of managing hardware devices (mouse, keyboard, printer, scanner, CD/DVD recorder,... ) that are connected to the computer. For example, you would need AC97 Audio Codecs for your Realtek soundcard to work properly.
Update your Realtek AC97 audio drivers
Nowadays, the majority of components that we connect to the computer are Plug&Play, this means, they are ready to be plugged in and used without having to install controllers. Furthermore, the operating system usually provides the majority of the drivers necessary. But in some cases, you may need to make use of the specific driver provided by the manufacturer.
AC97 Audio Codecs are the latest drivers available to optimize how the Realtek AC97 sound cards work on Windows Vista and Windows 7. These sound cards have been integrated in quite a few motherboards in the last few years.
If you've lost your motherboard's original CD or you want to have the latest official update to your Realtek sound cards drivers, you can now download them for free.