80+ PSU explain plz

Forever Oleg · Jul 18, 2015

I know how they work but what about the 80+ efficiency. Is it at idle or under load?

For example if I had a 350 watt system and had 400 watt PSU, will that PSU work if the PC under load, or 400*0.8=320watt will it not be enough?

fkr · Jul 18, 2015

the efficiency does not mean anything in regards to how much power it can make for your system. if it is a 500 watt power supply it will make 500 watts for your system

the efficiency just means how much power it will take from the wall socket to make that 500 watts. the more efficient the power supply the less power it needs from the wall to make the rated power for your system

nukemaster · Jul 18, 2015

fkr :

THIS all the way.

80+ is all about lowering wasted power(thus lowering heat output), NOT output power.

80+ sets a curve of efficiency at certain load levels(I think it is 20, 50 and 100% load). Almost all power supplies are more efficient at 50-60 percent load. Passive power supplies tend to be more efficient near max load.

EDIT.

Dropping in an image from wikipedia because it seems to be the right numbers

https://en.wikipedia.org/wiki/80_Plus

Zerk2012 · Jul 18, 2015

Forever Oleg :

Your looking at it wrong it has nothing to do with the power the PSU can provide but the ratio of Watts drawn from the wall outlet to the Watts supplied to the PC.
Example 100 Watts from the wall through a 80+ PSU will deliver 80 Watts to the PC,
When you have questions like this I always recommend you do some reading it will expand your knowledge.
Read this https://en.wikipedia.org/wiki/80_Plus

Forever Oleg · Jul 18, 2015

Thanks to all of you guys

I have been looking at PSU the wrong way this whole time

nukemaster · Jul 18, 2015

Do not feel bad many shops tell customers that the higher the 80+ level the more powerful the unit(ie, you should get at least an 80+ gold for gaming systems, silver will not cut it[total lie. The 80+ gold will use less power however]). I also see the same thing said all over the internet.

You want to look at the 12 volt rail.

Older units(many still sold at bargain prices for a reason. Entry level units will also have lower 12 volt current ratings) will have smaller 12 volt rails because older systems used 3.3 and 5 volts more, but modern systems make heavy use of the 12 volt rail(cpu/video card being the big ones).

If a power supply has multiple rails(heads up they are all fed from one large 12 volt rail). You will want to see the combined(adding rails only works on a small number of power supplies) rating as well(list in either watts or amps). If it is watts you can divide my 12 to get amps if it is amps you can multiply by 12 to get watts.

Example image(multi rail unit). As you can see adding the rails would lead one to think 30 amps(360 watts out of a 300 watt unit....no).

So 22A @ 12 volts(22 x 12) = 264watts
and 264 watts @ 12 volts(264/12) = 22amps

Always remember to check reviews on units because some are just bad and do not even deliver what the label says.

Forever Oleg · Jul 18, 2015

nukemaster :

Do not feel bad many shops tell customers that the higher the 80+ level the more powerful the unit. I also see the same thing said all over the internet.

You want to look at the 12 volt rail.

Older units(many still sold at bargain prices for a reason. Entry level units will also have lower 12 volt current ratings) will have smaller 12 volt rails because older systems used 3.3 and 5 volts more, but modern systems make heavy use of the 12 volt rail(cpu/video card being the big ones).

If a power supply has multiple rails. You will want to see the combined(adding rails only works on a small number of power supplies) rating as well(list in either watts or amps). If it is watts you can divide my 12 to get amps if it is amps you can multiply by 12 to get watts.

So 22A @ 12 volts(22 x 12) = 264watts
and 264 watts @ 12 volts(264/12) = 22amps

Always remember to check reviews on units because some are just bad and do not even deliver what the label says.

Thank you for the explanation. i didnt understand the concept but I know what PSUs are good out there.

I will be getting a VP 450 for my budget build

nukemaster · Jul 18, 2015

I added some extra information while you posted.

Do not hesitate to ask about power supplies for builds here.

Some users around here are always keeping and eye on what they sell and whats the best for the price.

Forever Oleg · Jul 18, 2015

nukemaster :

Yep. I earned badges of Graphics Card and CPU expert. I really know that stuff. I am not good with PSUs and overclocking though so yeah

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