Sunon (PF40561BX-Q40U-S9H) FAN-0163L4 is a standard fan for 1U 4-GPU series chassis. This fan has been fully tested and validated by Supermicro to ensure the best quality and cooling performance. - Sunon Counter-Rotating Fan - 40 x 40 x 56mm - Compatible with 1U 4-GPU Series Chassis - Fan Speed: 23,300 RPM / 20,300 RPM - Supermicro Certified