The Guru of 3D published a review on the Corsair RM650 Watt Gold PSU
A quote from the article:
We review the Corsair RM 650 GOLD power supply. Yes, the silent and even high-end RM 650 comes Gold certified, that means it's 90% efficient at 50% load. Efficiency matters. The PSU itself is even 100% modular, for most of you with a side panel window in their chassis a must really as you'll want modular cables. The PSU also improved on the audibility front. Have a peek at the article. Corsair has many PSU lines these days, it is a large chunk of their business. Amongst the product lines there is the Corsair Professional Series RM PSUs. The SKUs are re-injected into that always updating line-up.Corsair RM650 Watt Gold PSU Review @ Guru3D
Now it doesn't stop there though, the RM 650 might be an all silent model, but also comes with LINK options as well. The RM series are all about being quiet and efficient for a reasonable price. As such you'll notice that the PSU as tested today carries a Gold certification. Bronze, Silver but really Gold or Platinum is what you want, the upper stack in hardware is expensive though. Gold certified, that means it's 90% efficient at 50% load. Efficiency matters; years ago PSUs were as low as 70% efficient, meaning that 30% of the used power simply vanishes, whilst you are paying for it on that electricity bill. If your components eat away 500W then with that 70% efficient product you'd actually use 650W. The PSU itself is 100% modular as well, for most of you with a side panel window in their chassis a must really as you'll want modular cables. The PSU also improved on the audibility front as the fan doesn't even spin until it reaches a certain load or temperature, so if your PC is in idle and pretty much doing nothing, the rather silent fan will actually disable itself. That's right, the thermally-controlled fan spins up gradually above 40% load thus up-to 260 Watt power consumption this PSU makes no noise whatsoever, but even during normal use and when gaming it remains silent really.