F

Fan Rating     Airflow in cubic feet per minute. A 100% increase in airflow will reduce system operating temperatures by 50% relative to ambient. For each 10°C (18°F) reduction, the life of the system is doubled. (Arrhenius equation)

Fault Mode Input Circuit     The input current to a power supply with a short circuit on the output.

FCC - Federal Communications Commission     The US Federal Communications Commission specifies the maximum amounts of conducted noise signals (EMI) and radio frequency interference (RFI) that computer equipment is permitted to generate in Part 15 of the FCC Rules and Regulations. These limits are set in order to prevent computer equipment from interfering with the operation of radio and television receivers. Two different limits have been set, depending on the typical application and marketing of the computer equipment. The class "A" FCC limits are for equipment intended for use in commercial and industrial environments. The more stringent class "B" limits are for residential environments where TV and radio interference is more of a problem. Most personal computers are required to meet the class "B" limits since they are often sold for home use. Sale of such equipment requires that the manufacturer receive a FCC CERTIFICATION letter and registration number. Larger mini-computers and networking equipment are only required to meet class "A" because they are sold for commercial use. Compliance with the FCC class "A" limit need only is verified by the equipment manufacturer. http://www.fcc.gov

FCC Certified     A statement of compliance with US FCC class "B" limits for radio frequency emission, which is issued by the FCC and accompanied by a FCC "registration" or "ID" number. Certified equipment must be marked with the ID number. Personal computer equipment marketed to the residential user must be FCC certified.

FCC Verified     Equipment, which has been tested by either the manufacturer or an independent laboratory, found to be in compliance with the FCC class "A" limit for emission. Computer equipment that isn't required to be FCC CERTIFIED is required to be verified to the less stringent class "A" limit. Equipment, which may be verified, includes mini-computers, network file servers, and other network equipment.

Ferroresonant Power Supply     Power supply used at higher power levels in fixed applications, since they are very heavy. Can only be used effectively when the line frequency is very stable as they are sensitive to variations of input AC frequencies.

Filter     An electronic device that allows only certain frequencies to pass.

Firmware     A software program that is stored in semiconductor memory, such as read only memory (ROM) integrated circuits. Such programs are often embedded in hardware systems for control applications.

FlexATX     FlexATX: a new addendum to the microATX form factor. This new mainboard (7.5" x 9") form factor uses all of the same high performance of microATX, but allows for use in a much smaller space. It has no slots, no connectors and a highly integrated design. 'Flex' refers to flexible and this new form factor has the following goals in mind: leverage benefits of legacy removal, higher feature integration, more reliable and allows for more consumer look and feel consideration in smaller PC enclosure designs. This reduced chassis size improves the aesthetic value for the end-user and is intended to promote higher satisfaction with system ownership. For more info check out Intel's http://www.teleport.com/~ffsupprt/.

Foldback Current Limiting     A power supply output protection circuit whereby the output current and voltage decrease with increasing overload, reaching a minimum at short circuit.