StarTech.com 80x25mm Dual Ball Bearing Computer Case Fan w/ TX3 Connector (FANBOX2) - system fan kit

The StarTech.com 8cm x 8cm x 2.5cm (3 1/8" x 3 1/8" x 1") PC case fan is an add-in cooling fan designed to fit most computers. It can be used to circulate cool air into the case or exhaust warm air out, preventing problems due to overheating components. A quiet running brushless ball bearing DC motor coupled with a high efficiency blade design is capable of moving 32 CFM (cubic feet per minute) of air. Power is supplied to the fan using a 3-lead TX3 connector that plugs into the motherboard and allows the system to monitor fan speed and operating status.

Price: 5.98 from Currys Business