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Is it true- PSUs run max efficiency at 40-60% Load?

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a b ) Power supply
March 8, 2012 4:43:43 AM

Article about PSU efficiency
Quote:
If you see a typical efficiency curve, you will notice that efficiency varies according to the power being delivered. Usually, the power supply achieves its highest efficiency when delivering between 40% and 60% of its maximum capacity. Efficiency is also higher when the power supply is operating at 220 V.


So if I were to build a small system that consumes about 350w at the most, would 500w to 600w be the sweet spot for efficiency?
a c 110 ) Power supply
March 8, 2012 4:49:24 AM

Old article...
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a b ) Power supply
March 8, 2012 4:55:52 AM

amuffin said:
Old article...

Which is exactly why I'm asking if this still applies to PSUs today.
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a c 110 ) Power supply
March 8, 2012 5:00:34 AM

It should be roughly 80-90% that is why we have 80+ ratings.
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a c 139 ) Power supply
March 8, 2012 5:17:35 AM

It's still true:

Corsair TX650 V2
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a c 139 ) Power supply
March 8, 2012 5:24:58 AM

e56imfg said:
So if I were to build a small system that consumes about 350w at the most, would 500w to 600w be the sweet spot for efficiency?
With a good PSU the sweet spot might be larger than just the 40%-60% band.
In that Corsair TX650 V2 chart I used for example the range of efficiency is still at 82~83% as low as 20% and as high as 100%.
If efficiency is the prime reason for choosing a PSU of the same quality would expand the range of PSUs from 400W and up.


That Acoustic/Noise chart is something to consider as well. Staying under 32~35dBA is a pretty good result.
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a b ) Power supply
March 8, 2012 5:45:25 AM

amuffin said:
It should be roughly 80-90% that is why we have 80+ ratings.

Isn't 80+ the efficiency you pull from the wall to the max rated wattage. 300w produced from a 600w PSU at 80% efficiency = 360w from wall?

The sweet spot is the 50% to... 80%?
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a b ) Power supply
March 8, 2012 5:53:36 AM

e56imfg said:
Isn't 80+ the efficiency you pull from the wall to the max rated wattage. 300w produced from a 600w PSU at 80% efficiency = 360w from wall?

The sweet spot is the 50% to... 80%?


looking at the curves posted above, pay attention to the left hand scale, the best efficiency is 50% BUT there is only a 1-2% drop off on either side between 20% and 100%.

In the past the value would have been a lot lower and the curve a lot more pronounced, since everything is getting closer to 100% the curve is getting flatter. In terms of costs, you'd benefit more from getting a PSU and mobo that is at zero power when off, my server on an old PSU for instance draws about 15W from the wall whilst off, and that is 100% down to the PSU being old.
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a b ) Power supply
March 8, 2012 6:00:29 AM

13thmonkey said:
In terms of costs, you'd benefit more from getting a PSU and mobo that is at zero power when off, my server on an old PSU for instance draws about 15W from the wall whilst off, and that is 100% down to the PSU being old.

Uh... More explanation please? :??: 

Still trying to learn this PSU nonsense :p 

What do you mean "you'd benefit more from getting a PSU and mobo that is at zero power when off" Isn't that impossible without unplugging the cord directly? Do you mean I should get a PSU that has a lot of headroom or just a little bit of headroom?
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a b ) Power supply
March 8, 2012 6:25:37 AM

get one that has a good amount of headroom tell us your system specs.

some psu's have the ability to draw zero/near zero when the PC is off, mine draw about 15W, buts that every hours of the day when it is not on. Getting one of those would do far more for you in terms of power savings than being at 82% vs 81.5%.

Also note that at idle a PC is drawing perhaps 75-125W depending on the age of the system, and that unless you turn it on, game, turn it off again most of its time will be spent at idle, so you need something that is efficient at 75-125W and at maybe 300W depending on your system. so the very flat curve that WR2 posted is fine. All 80+'s will have a similar curve, as its too expensive to go much above 85%, and they aren't allowed to go below 80%

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a b ) Power supply
March 8, 2012 9:17:48 AM

When your PC is OFF the only draw is very small. There's not enough draw to worry about efficiency.

When you PC is in STANDBY that's a different matter, but still not enough to worry about efficiency.

If your PC is at idle for long periods at 90W, the potential differences of various PSUs may cost you a few dollars over the course of a year. You might save 5W there... so it would be a similar cost to that nightlight.

Say you are gaming with a 2500K and 6950, both overclocked. Now you may be averaging 300W in a game. Saving 15W with a very efficient PSU, during the 4 hours you average per day, because you are fairly hardcore, still might not mean too much... but your more efficient PSU generates less heat also, and is usually quieter because it doesn't need a loud fan.

So do you need the most efficient PSU? Probably not. The more efficient PSUs are often the best performing in those more important areas though. And of course there is the environmental impact of the 15,000,000 watts saved by gamers nightly.

Check out this Superflower unit - 89.8% to 91.5% efficiency... that's only a 1.7% variation.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=...

So in that case, where you happen to fall on that curve is not going to make a lot of difference.
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March 8, 2012 11:38:57 AM

Silver rating: 85%/89%/85% -20%/50%/100% load
Gold rating : 88% /92%/88%- 20%/50%/100% load
Platinum rating: 90%/94%/91%- 20%/50%/100% load.
(For 230v ).
So the best efficiency would be around 50% load.
And at full load efficiency is still very good.
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a b ) Power supply
March 8, 2012 7:58:47 PM

Right now I'm running a small HTPC from HP.

I want to get the best possible efficiency for my upcoming system (who wouldn't?). After a year of extensive research, I have saved up enough to get a nice $1000 - $1500 build.
I am not much of a gamer. I base my system on machinery models and samples I receive from my courses.

Case: CM Storm Trooper or Corsair 550D
Case fans: a few Silverstone AP 141
CPU Cooler: Hyper 212 Evo
CPU: Ivy Bridge 3770K or non-K if I get interested in OCing
Motherboard: Z77, even if I'm not OCing.
RAM: Low-profile 16GB Vengeance
GPU: I will reuse my small 6570 since it's dead silent and still good condition
HDD: 1.5TB WD Green
SSD: 60GB M4

I still do some light gaming once in a while (Minecraft- such a fun little game!). But since MC is based on Java, the CPU will do most of the work.

Now I've got everything planned out except the PSU. I do not want to go cheap on a PSU so I will spend whatever is needed to get the maximum efficiency of my system- I am on my journey to become an environmentalist so conserving the environment is a huge factor for me (that's why I 'm going with Ivy Bridge)

So based on eXtreme Power Supply Calculator Lite, about 350w will be drawn on peak load (which I doubt I'm going to ever reach). I have in mind that Ivy Bridge isn't even out yet, but based on the rumors, it seems it will have less TDP.
How many Watts will my system be pulling from the wall at idle? About 50w to 90w? So does that mean I should go with an efficient 380w PSU? Antec EA-380w
But I most likely will be upgrading the GPU after Keplar releases and the prices start to fall- I will get the next gen 570 or 560 ti. So based on the Radeon 7000 (their TDP will be mostly the same right?), they will have a bit less power consumption.
P.S- A higher end GPU will help eliminate bottlenecks and time waiting for models to load- not going with any workstation GPUs
But to reach maximum efficiency for my system + new GPUs, will I need a 600w to 700w PSU?

Thankx
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a b ) Power supply
March 8, 2012 8:34:18 PM

Your other factors need to be considered, beyond wattage. 380W is awfully generous for that system, but I would probably look at something a bit larger. You need cables for one thing.

It's an EA-380D, not W... the D meaning Delta, the OEM. Old design, and a long way from a top of the line PSU. It's a great budget choice though.

This brand new EA-450 Platinum is made by FSP:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
So I would need to see a review before I recommend it.

This Seasonic fanless 460W is incredible at this price, but it ends today:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
That's probably the best PSU you can get for this build.
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a b ) Power supply
March 8, 2012 11:10:57 PM

Proximon said:
Your other factors need to be considered, beyond wattage. 380W is awfully generous for that system, but I would probably look at something a bit larger. You need cables for one thing.

It's an EA-380D, not W... the D meaning Delta, the OEM. Old design, and a long way from a top of the line PSU. It's a great budget choice though.

This brand new EA-450 Platinum is made by FSP:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
So I would need to see a review before I recommend it.

This Seasonic fanless 460W is incredible at this price, but it ends today:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
That's probably the best PSU you can get for this build.

Wow that's a lot of money :o  , but you get what you pay for.

So in conclusion: the peak efficiency is 50% to about 80% and I'll just get a large 460w or 500w PSU.

Thank you everyone!
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a b ) Power supply
March 8, 2012 11:11:16 PM

Best answer selected by e56imfg.
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a b ) Power supply
March 9, 2012 6:41:13 AM

e56imfg said:
Wow that's a lot of money :o  , but you get what you pay for.

So in conclusion: the peak efficiency is 50% to about 80% and I'll just get a large 460w or 500w PSU.

Thank you everyone!


no in conclusion peak is between about 30% and 80% with slightly better at 50%, but only slightly.
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March 9, 2012 2:59:55 PM

I just did two reviews that may help with this, in summary a power supply that is 80 percent efficient uses 20 percent of the power it is consuming not to power your computer but is lost in heat or just to power itself.

The more efficient a PSU the less heat is wasted by the PSU just to output power to your system. I did some calculations for an Antec EA-650 watt PSU using a Kill a Watt meter and found that I use 256 watts of power while stress testing my system running Furmark. When doing general computer work my system uses 100 watts so I could potentially save about $42 a year just for general computing because I am using an energy efficient PSU. When gaming and other high demand processes the savings will vary but at the least with a higher efficiency PSU I can save that $42 a year on my one computer with my computer usage in a day.

That may not seem like a lot when spread out over a year or by the month but if you start doing small savings here and there it does add up.

The second review I did was for a smart or advanced power strip from TrickleStar that has one outlet as a control to turn off other outlets. The control outlet is used to turn on and off others, I have one on my entertainment center and have received others to test out in various ways. When I turn on my TV the power strip turns on other outlets that have my Wii, speakers with a bass and a Wii controller charging base that saves me about $7.40 a year just from turning off the Wii, speakers and charger when the TV is not in use.

I tried to use this on my computer but the computer is not a large enough change in wattage between on and off for the outlet to recognize the on and off states of the control device but I am going to try a different setup where I turn on and off my monitor that will control my computer and other PC peripherals from getting power.

If you start to save money here and there your money will be more available for you to spend on better things instead of on wasting it to heat or to devices that are not even being used.

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a b ) Power supply
March 9, 2012 3:06:10 PM

I used one of those switching plugs on a PC, it worked fine, except when I wanted to use my monitor on my laptop, so I gave up in the end. But it can work on a PC.
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