The Corsair GOLD certification (quality and silence).

Certainly, it is almost double of a Corsair CX, but the choice is justified. If you want security and a seamless supply which delivers continuously at least 86% of power from its power setting, you need a certified Gold like this (obviously depending choose the components you need feeding - if you have many devices will require a more powerful, such as the model 700 W). These Corsair RM models have this interesting distinction of being FANLESS when the power demand is below 50%. Thus, there is no noise from this side (to study when you do the total power necessary for the PC that you mount). Ideal for a NAS (food quality and output current) or a HTPC (silence).