Generally speaking, the higher the efficiency of your power supply the more you pay. The highest efficiency you can currently find on the mass market is the 80PLUS Gold range of power supplies. These supplies have efficiencies peaking into 90% or above - meaning the power coming from your wall is being well used, not wasted. The majority of 80PLUS Gold power supplies will run you about $120CDN and up, and most are also higher wattages, 600Watt plus, which are great for higher end systems but a waste of money for a more mainstream setup. Only a couple months ago FSP came to market with the Aurum series of 80PLUS Gold certified power supplies. The Arum models start at lower wattages, and lower price tags, than most other 80PLUS Gold power supplies. Here today I have the base 500W model - a great contender for mainstream systems that want to save on their electricity bills without paying an unnecessary price for a power supply that's way more powerful than they really need.