http://www.stormcam.org/electricity-usage/

Is it a diet more electricity for other uses?
300w psu as a small as opposed to 620W. What the 620W 620W use or is it the total of all components to use?
Yes and no. UAP work best at a certain load, usually 40% -80%. A small charge is inefficiency, and high load causes a stress on components. Both are shot more power than it needs. A replacement of a 620W 300W is close to the max will be more effective. It will probably use new technologies too. OTOH, replacing a 300w is not working hard with a 620W will probably lead to the use of higher power, and worse still Details of tension. Most supplies of electricity does not handle light loads well. But a bigger power supply does not automatically take all the power it says it can provide. — I guess the 620W Corsair HX620W is? A diet very solid.)
Minecraft Alpha – Electricity – The Best Use