The KCU1500 cooling fan connector is shown in This Figure, located between callouts 13 and 15.
The KCU1500 uses a TI LM96063 (U53) fan controller, which autonomously controls the fan speed by controlling the pulse width modulation (PWM) signal to the fan based on the die temperature via the FPGA's DXP and DXN pins. The fan rotates slowly (acoustically quiet) when the FPGA is cool and rotates faster as the FPGA heats up (acoustically noisy).
The fan speed versus the FPGA die temperature algorithm along with the over temperature (OT) set point and fan failure alarm mechanisms are defined by user values programmed into the LM96063 device register set. The LM96063 OT TCRIT# output is wired to a MAX16052 (U52) supervisory device that turns off the KCU1500 power system voltage regulators if an OT condition is detected.
See the LM96063 [Ref 15] data sheet for more information on the device circuit implementation on this board.