The performance parameters have a direct impact on the "220V Cooling Fan" of the air flow, which represents an allowable range of the larger diameter of the fan, then the greater the capacity of the fan, the greater the effect of surface wind effects ??? Reserve position in the mainframe typically is installed 8cm × 8cm axial "220V Cooling Fan", if not in the standard mounting position is not the limit, so then we can choose a slightly larger size of the fan. For this indicator, I want to say is to choose the fan diameter must be coordinated with its own computer chassis structure to ensure "220V Cooling Fan" does not affect the normal operation of other computer equipment and computer chassis to ensure that there is enough free space to facilitate disassembly other accessories.