My motherboard (Asus A8N-SLI Deluxe) has the following fan connectors:

CPU_FAN
CHA1_FAN
CHA2_FAN
CHIP_FAN
PWR_FAN

As it stands, I only have the heatsink fan plugged into the CPU_FAN connector. My chassis fans are both stock fans and don’t come with any motherboard connectors. Are there any other fans that MUST be plugged into the motherboard?

A8N-SLI Deluxe

From my reading of the Manual

The on-board fan connectors are required for monitoring temps & rpm & auto start & stop features.

There is one mention in the BIOS setup that unconnected fans will show "0".

sorry but this pdf doc won't allow copy/ paste