I swapped my two NZXT AER exhaust fans in my H500i with a Noctua NF-A12x15 120mm PWM (back) and a Noctua 140mm NF-A14 PWM (top). CPU is a few degrees cooler, but
NZXT Aer RGB review: these case fans are pretty, clever - Review - Coolers | XSReviews
NZXT AER RGB 2 - 120mm - RGB LED - Fluid Dynamic Bearing - PWM Fan for Hue 2 - Single - Newegg.com
NZXT Aer F120 120mm High-performance Airflow PWM Fan
NZXT AER RGB120 and AER RGB140 - Test and Review -
NZXT H510 Flow Mid-Tower Case (White) CA-H52FW-01 B&H Photo Video