500W modular Power Supply Module , hot plug, titanium (96% efficiency) for tower servers. This 500W PSU comes with an adjusted firmware for optimized fan control and reduced acoustic noise. The fans are triggered later and slower, which helps improve the overall acoustic behaviour of the tower servers. The PSU is intended for tower servers only. Mixed configurations with PYBPU503/ PY-PU503 within one system are not permitted due to different firmware.