How-To Geek on MSN

PSA: You need a rear fan on your PC

Unlike other case fans, the one in the rear isn't optional.
PC World

CPU-FAN versus CPU-OPT on motherboards: What’s the difference?

The CPU OPT header is an additional connection for special processor cooling accessories, such as specialized coolers with multiple fans or water-cooling components. Functionally, CPU OPT is identical ...