Software monitors are more commonly seen, sometimes as a part of a widget engine. These monitoring systems are often used to keep track of system resources, such as CPU usage and frequency and the amount of free RAM. They are also used to display items such as free space on one or more hard drives, the temperature of the CPU and other important components, and networking information including the system IP address and current rates of upload and download. Other possible displays include the date and time, System uptime, computer name, username, hard drive S.M.A.R.T data, fan speeds, and the voltages being provided by the power supply.
Less common are hardware-based systems monitoring similar information. Customarily these occupy one or more drive bays on the front of the computer case, and either interface directly with the system hardware or connect to a software data-collection system via USB. With either approach to gathering data, the information is displayed on a small LCD panel or series of small analog or LED numeric displays. Some hardware-based system monitors also allow direct control of fan speeds, allowing the user to quickly customize the cooling in the system.
A few very high-end models of hardware system monitor are designed to interface with only a specific model of motherboard. These systems directly utilize the sensors built into the system, providing more detailed and accurate information than is customarily available to less-expensive monitoring systems.
Software versions are becoming more common, with even the Microsoft Windows Vista sidebar including a meter to monitor CPU and RAM usage. Hardware versions are very rare on OEM computers, with the exception of very high-end servers. However, these monitors are often installed by the large and active computer enthusiast community.