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Chassis and CPU fans may use either 3-pin or 4-pin power connectors. 3-pin connectors are usually used for the smaller chassis fans with lower power consumption. 4-pin connectors are usually used by CPU fans with higher power consumption.
Fans and on-board fan headers are backwards compatible. Proper fan connector placement is shown in the figures below.
Fan has a 3-pin power connector; desktop board has a 4-pin fan header:
Note: when using a 3-pin power connector with a 4-pin fan header, the fan will always be on; there is no fan control.
Fan has a 4-pin power connector; desktop board has a 3-pin fan header:
This applies to:
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