EggXpert

What is the most power efficient PSU available, especially at 750 W and above.  I was wondering because any slight efficiency advantage that one PSU has over another could eventually cost me hundreds of dollars, due to the fact that electricity costs a little above twice the national average in the rural Alaskan village that I live in.

 Thanks in advance for any help received.

I say the Thermaltake Toughpower W0172RU 850W ATX12V / EPS12V Power Supply with up to 87% efficiency is about as good as your going to get. Yet the efficiency spec on most power supplies is generally a misleading number because unless you see the efficiency data points for a range of powers on a power supply it's really quite hard to tell how truly efficient it is.

Reactor89

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Those that say they know everything, may lose everything they know.

It isn't that single rails are more efficient but that multi=-rails configurations can have lost power due to how they are designed as each rail provides a set number of Amps.  Due to this, it is possible for the power draw from your devices to exceed the number of available Amps which is the biggest reason people now recommend single rail PSUs as single rail PSUs can deliver the power where it is needed without being bottlenecked.  Also multi-rail PSUs can have under-utilization on some rails and have wasted power there.  As such, here is the 80+ certified single rail PSUs on Newegg.  3 of the PSUs, all at 750W, are the same model but in different colors.  There is an 860W PSU as well on the list as well.  These first 4 PSUs are from PC Power & Cooling which is one of the top brands for power supply units.  The last one on the list is a 750W unit from Corsair.  Again, all are 80+ certified which means you will have better efficiency from them with less power loss.

 http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2010320058%201409730089%201230113790&bop=And&Order=BESTMATCH&CompareItemList=N82E16817703019%2CN82E16817341011%2CN82E16817139006%2CN82E16817703013%2CN82E16817703009

I guess in the end we should really clarify the question. Do you want a power supply that is effective in dishing out large sums of power or do you want a power supply that is efficient so it can help you conserve energy. If you have a high-end power hurry computer that needs to be feed tons of power all the time, the effective nature of the single rail design is the way to go. If your looking to do more with less power on a computer that doesn't consume large amounts of power all the time, the efficiency percentages are the important spec in a power supply. Yet I will also reiterate that efficiency specs are misleading unless there coupled with a power measure. An example being: a power supply is 85% at 500 watts. For the best results a good computer builder could figure out the average energy consumption of a computer and get a power supply that has it's peck efficiency at that average point. This can provide most long term savings in power but tends to be hard and time consuming to figure out. 

Reactor89

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Those that say they know everything, may lose everything they know.

I agree with Tekran, rails really have nothing to do with efficiency, unless the power supply is made up of two smaller power supplies(some higher wattage power supplies do this).  In most cases, multi-rail power supplies have one single 12v rail which is divided up with over current protection sensors on the rails that will shut the power supply down if the current on a certain rail goes too high.  As long as the current stays below the set limit, multi-rail power supplies behave exactly the same as single-rail power supplies.  

Currently, some of the most efficient high-wattage power supplies on the market are the Cooler Master Ultimate / UCP power supplies.  The Cooler Master UCP 900watt unit is the first high-wattage power supply to ever achive the 80 Plus silver ranking.  According to 80Plus testing, it has a typical efficiency of over 88%, which is truly amazing.   Even at its highest peak efficiency, the thermaltake model that Reactor89 linked never even reaches 88% efficient, while over 88% efficiency is typical for the Cooler Master. 

If that's too expensive for you, the higher wattage Cooler Master Real Power Pro power supplies ( >800watts) have a very efficient design.  They have >85% efficiency typical, and this has been verified by testing at JonnyGuru.com. 

Also, other very high efficiency power supplies, comparable to the Cooler master UCP power supplies(or perhaps even a little more efficient), are the Enermax Revolution power supplies. 

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