Why install the extra fans in front of the condenser? At highway speeds they're likely little more than a hinderance to the flow of cooling air anyhow. I don't know what humming sound you're referring to but what is your concern?
Ultimately, my advice is to remove the extra electrical fans you installed and if you want to increase airflow through the radiator I'd get an upgraded fanblade like GKtech sells.
This is what I'm referring to:
https://us.gktech.com/sr-ka-rb-vg-high- ... e-air-flow
Generally speaking the belt driven fan is going to be the best performer. If you're having overheating issues it's likely due to another issue like a stuck thermostat or airflow restriction in which case, throwing additional fans at the problem isn't going to solve it anyhow.