How does the Bronze/Silver/Gold PSU rating work?

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hunter315
The farthest left data point is the 10% load that JonnyGuru collects in their reviews, no one measures below that, though the 5VSB which is always on has become rather efficient in recent years, it used to be ~70%, now they are nearly 80% at 4A which is quite good for a cheap little circuit.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=376

The reason no one pays a ton of attention to super low load levels is because it doesn't matter. Lets take a system that is 50W at idle and 500W at load. The difference between having a PSU that is 85% vs 75% efficient at 50W is only 7.86W/hour, the difference between having a PSU that is 90% vs 88% efficient at 500W is 12.63W so the 2% efficiency difference at load results in...
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rolli59

rolli59

Titan
Oct 27, 2007
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It is an efficiency rating or basically how much more it will pull from the wall than its rated output.
Example 500watt 80% efficient will pull 625watts from the wall at full load! at 90% efficiency the same PSU would do 555 watts from the wall!
 
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hunter315

hunter315

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May 12, 2009
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90+ is a bogus marketing term, 80 Plus is run by Ecova and gives out certifications to power supplies based on the efficiency they manage at 20, 50, and 100% load.

Recently there became 6 tiers to it, from basic through gold, platinum, and titanium.

For an end user, the price difference between a Bronze and a Gold unit will almost never pay for itself in energy savings over the life of the unit so don't go and buy an 80+ titanium unit thinking it will pay for the price difference, it never will. 80+ became a thing because it is very useful to the power companies(less capacity required) and is useful for corporations. In a large office that requires AC you pay for all the power your computer uses twice, once to power the computer, and a second time to run the AC to remove that heat from the building, for massive call centers running at 90% instead of 80% can make a big difference in overall facility power consumption in the summer.

I have a post about PSU efficiency myths, you can find it in my signature.
 
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skit75

skit75

Splendid
Oct 7, 2008
2,684
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I believe there is a Platinum rating also.

The important thing to know is efficiency is based on a curve. You want to accurately determine what load you will likely be using in your rig and try to match a supply that benefits the efficiency curve. Power supplies lose efficiency as the load drops and typical efficiency ratings vary between 50-70% loads. Extra energy not used by the supply is dissipated as heat. Less heat equals a longer life and a quieter running supply.

Another Wiki for Efficiency http://en.wikipedia.org/wiki/Power_supply_unit_(computer)
 
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hunter315

hunter315

Champion
May 12, 2009
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The curve argument is bogus and just results in people grossly oversizing their PSU. You should oversize a bit to give it some headroom to allow for component aging, but sizing to be at 50% is just silly. Efficiency tends to only drop by about 2 percentage points from 50% load to 100% load. A few years back i plotted this with an honest Y-axis, not zoomed in like most people do.
honest.jpg

I'd say thats pretty damn flat from 20-100%
 
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Dark Lord of Tech

Dark Lord of Tech

Retired Moderator
Aug 18, 2009
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Power supplies are the devices that power computer, servers and data center devices. They convert AC power from electric utilities into DC power used in most electronics. The 80 PLUS® performance specification requires power supplies in computers and servers to be 80% or greater energy efficient at 10, 20, 50 and 100% of rated load with a true power factor of 0.9 or greater. This makes an 80 PLUS certified power supply substantially more efficient than typical power supplies.

Plugandload
 
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hunter315

hunter315

Champion
May 12, 2009
10,653
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51,960
The farthest left data point is the 10% load that JonnyGuru collects in their reviews, no one measures below that, though the 5VSB which is always on has become rather efficient in recent years, it used to be ~70%, now they are nearly 80% at 4A which is quite good for a cheap little circuit.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story3&reid=376

The reason no one pays a ton of attention to super low load levels is because it doesn't matter. Lets take a system that is 50W at idle and 500W at load. The difference between having a PSU that is 85% vs 75% efficient at 50W is only 7.86W/hour, the difference between having a PSU that is 90% vs 88% efficient at 500W is 12.63W so the 2% efficiency difference at load results in 60% more waste heat than the 10% efficiency difference at idle, much larger power savings gains can be had by improving efficiency where there is a significant quantity of power in play.
 
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