asus hero viii SLI fan connector 4 according to manual

[gianquittia]

Hi.
I have a second 980 TI incoming and in the manual it says if you have dual GPU to plug one fan into connector 4. Is there a reason for this? Right now I have a fan adapter and nothing is connected to connector 4. Will that be a problem?

[Chino]

To better the airflow.