Coolermaster v650 semi modular 80 plus gold power supply the rotation speed stays lower in the silencio while delivering high air pressure meaning less noise after 50 load the rotation speed difference compared to double ball fans is 16 better in the v750 22 in the v650 and 34 in v550 the 12v rail is the most important part of a modern power supply as both the cpu and graphic cards are powered through it voltage fluctuations can cause system instability from high pitch noises