The Most Efficient Output Point Of PSU Load

[_Hustler_One_]

Hello everyone..

I wonder if this statement is true or not. I've read (forgot which the source is) about PSUs that says, ~The highest point of "80+ Gold rated PSU" efficiency will be reached when its load is at around 50% of its rated power~ So for example a 80+ Gold 650W PSU will be at its highest efficiency at around 325W load.

Is this statement true?

[Sakkura]

It depends on the power supply. What is definitely true is that efficiency drops closer to 0% load as well as (almost always) closer to 100% load. So obviously there's a point in-between with the highest efficiency. But it doesn't have to be at 50% load, it can be at 70% or whatever.

[Bananasplit_00]

really depends on the PSU but thats in generall where the peak efficiency is if you look at the graphs

[Jurrunio]

All electronics reach their most efficient state before their maximum ratings that's for sure, but it could be any value between idle and full load. It still depends on the overall design, especially when it comes to PSUs which has so many components.

[minibois]

As said above, it depends on your PSU and you can usually find out through the data spec sheet.

For example your PSU (the TX650M), Corsair listed its effeciency level at 10, 20, 50 and 100 percent and the level of effeciency (higher is better) is: 78,67%, 85,85%, 87,71% and 85,42% respectively.

So yea, in this case it is most effecient at 50% (in the 4 examples Corsair listed).

 

Note: this is at 230V, they also have a list for at 110V, which is a little different; but it paints the same picture in terms of erelative power consumption between the levels of load. Also, I am from Europe, so a comma might mean a dot for you.

[_Hustler_One_]

2 minutes ago, Sakkura said:

It depends on the power supply. What is definitely true is that efficiency almost always drops closer to 0% load as well as closer to 100% load. So obviously there's a point in-between with the highest efficiency. But it doesn't have to be at 50% load, it can be at 70% or whatever.

So If anyone use any PSU that supplies power more than their system maximum power draw they wont face any issues, the differences are only on the efficiency they're having. But how to get an idea if I want to get the most electricity efficiency from a PSU for my system, so I can have an idea of expected electricity bill of mine. I don't want it to be over-cost.

[Sakkura]

1 minute ago, _Hustler_One_ said:

So If anyone use any PSU that supplies power more than their system maximum power draw they wont face any issues, the differences are only on the efficiency they're having. But how to get an idea if I want to get the most electricity efficiency from a PSU for my system, so I can have an idea of expected electricity bill of mine. I don't want it to be over-cost.

50% isn't a bad rule of thumb to use. Just saying it's a rule of thumb, so don't be surprised if a particular unit is actually most efficient at 40% load rather than 50%.

 

If you want to know for a specific model you can check reviews, some provide an efficiency curve.

 

But in practice you probably don't need to get very specific about this. As long as you select a sane wattage, the difference this makes will be pretty small. Just don't go with 1000W for a single GPU.

[_Hustler_One_]

8 minutes ago, Minibois said:

As said above, it depends on your PSU and you can usually find out through the data spec sheet.

For example your PSU (the TX650M), Corsair listed its effeciency level at 10, 20, 50 and 100 percent and the level of effeciency (higher is better) is: 78,67%, 85,85%, 87,71% and 85,42% respectively.

So yea, in this case it is most effecient at 50% (in the 4 examples Corsair listed).

 

Note: this is at 230V, they also have a list for at 110V, which is a little different; but it paints the same picture in terms of erelative power consumption between the levels of load. Also, I am from Europe, so a comma might mean a dot for you.

If my system draws around 410W to get the highest efficiency of it is to get any 80+ Gold 800W PSU? The price wouldn't be worth it compared to the electricity bill save up, CMIIW

[Sakkura]

3 minutes ago, _Hustler_One_ said:

If my system draws around 410W to get the highest efficiency of it is to get any 80+ Gold 800W PSU? The price wouldn't be worth it compared to the electricity bill save up, CMIIW

If your system draws 410W at full load on both CPU and GPU, it will usually draw somewhat less at realistic loads like gaming. So you could base it on a power draw of 300W or 350W, thus going with like a 650W power supply.

[mariushm]

That statement USED to be true for regular power supplies.

 

Nowadays, it's no longer true. For GOLD efficiency power supplies, the efficiency curve is more like this :

 

Seasonic PRIME Series 750 W

https://www.techpowerup.com/reviews/Seasonic/Prime_750/6.html

 

 

 

So you can say the power supply has it's PEAK efficiency at 300w and close to 95% efficiency (so less than 50% of max load of 750w), but between 100w and 600w, you can see that the efficiency difference is less than 1% ... it's practically negligible.

 

BitFenix Formula Gold 750 W

https://www.techpowerup.com/reviews/Bitfenix/BF750F/6.html

 

 

Same story ... peaks at 300w out of 750w (less than 50% load) but between around 250w and 500w the power supply is 92% +/- 0.5% efficient, practically flat.

 

It's way different compared to older  BRONZE power supplies which had a more pronounced curve of efficiency, as you can see here:

 

Enermax NAXN ADV 650 W Review

https://www.techpowerup.com/reviews/Enermax/ETL650AWT/6.html

 

 

 

This is actually a DECENT bronze efficiency psu, there are worse. You can see this BRONZE efficiency psu peas at 89% at 250w (still a bit below half of the max of 650w) but there's a much higher difference between minimums and peak... you have 86% at 100w, 89% at 250w , and you're already down at 86% at 600w ... it's not half a percentage difference between peak and wide use range.

 

[_Hustler_One_]

3 minutes ago, Sakkura said:

If your system draws 410W at full load on both CPU and GPU, it will usually draw somewhat less at realistic loads like gaming. So you could base it on a power draw of 300W or 350W, thus going with like a 650W power supply.

Maybe The best PSU for my system if I want to get the most efficiency is a 80+ Gold 700W, right? Considering I'm running my system overclocked at all time.

[Sakkura]

2 minutes ago, mariushm said:

 

Here is a counterexample. Its efficiency curve (at 230V) seems to peak at over 250W, so significantly above 50% load.

 

1 minute ago, _Hustler_One_ said:

Maybe The best PSU for my system if I want to get the most efficiency is a 80+ Gold 700W, right? Considering I'm running my system overclocked at all time.

Possibly. There isn't much of a difference between 650W and 700W anyway.

[mariushm]

3 minutes ago, Sakkura said:

Here is a counterexample. Its efficiency curve (at 230V) seems to peak at over 250W, so significantly above 50% load.

 

Possibly. There isn't much of a difference between 650W and 700W anyway.

That's pretty much a model that uses a platform for higher wattage ... my guess is they wanted to have a 450w, a 550w and a 650w model in the series ... so they probably use the same hardware as the 550w with maybe a lower size main capacitor (which doesn't decrease efficiency, only reduces hold up time in case of power hiccups) and maybe cheaper fan.

4 12v rails each specc'ed for 25A ( 300w per rail, 450w in total) is just ridiculous.

[_Hustler_One_]

2 minutes ago, Sakkura said:

Here is a counterexample. Its efficiency curve (at 230V) seems to peak at over 250W, so significantly above 50% load.

 

Possibly. There isn't much of a difference between 650W and 700W anyway.

I'm currently building an ITX system, the planned specs are shown on my sig bellow. I choosed SeaSonic FOCUS Plus Gold 80+ 550W to adjust to the budjet which is wont be problems regarding the power it supplies vs system power draw. But if I want to get the best efficiency of the whole system, lets put PSU price aside, which PSU will give me the most efficiency for my ITX plan?

[seon123]

14 minutes ago, _Hustler_One_ said:

I'm currently building an ITX system, the planned specs are shown on my sig bellow. I choosed SeaSonic FOCUS Plus Gold 80+ 550W to adjust to the budjet which is wont be problems regarding the power it supplies vs system power draw. But if I want to get the best efficiency of the whole system, lets put PSU price aside, which PSU will give me the most efficiency for my ITX plan?

AX1600i. That thing is ridiculous. 94,2% efficient at 320W. 

That's higher than the any of the Seasonic Prime Titaniums at any load. 

https://www.cybenetics.com/index.php?option=database&manfID=28&volts=1

Edited October 14, 2018 by seon123
Something something

[_Hustler_One_]

7 minutes ago, seon123 said:

AX1600i. That thing is ridiculous. 94,2% efficient at 320W. 

That's higher than the any of the Seasonic Prime Titaniums at any load. 

https://www.cybenetics.com/index.php?option=database&manfID=28&volts=1

Great.. Thanks for the ridiculous recommendation.. That answers my question.

I think I threw the wrong question

[seon123]

2 minutes ago, _Hustler_One_ said:

Great.. Thanks for the ridiculous recommendation.. That answers my question.

I think I threw the wrong question

 

24 minutes ago, _Hustler_One_ said:

But if I want to get the best efficiency of the whole system, lets put PSU price aside, which PSU will give me the most efficiency for my ITX plan?

Probably. 

[_Hustler_One_]

7 minutes ago, _Hustler_One_ said:

Great.. Thanks for the ridiculous recommendation.. That answers my question

 

4 minutes ago, seon123 said:

 

Probably. 

you hit exactly the right spot!

 

lets talk about resonable ones from SeaSonic or Corsair

[17030644]

3 hours ago, Sakkura said:

If your system draws 410W at full load on both CPU and GPU, it will usually draw somewhat less at realistic loads like gaming. So you could base it on a power draw of 300W or 350W, thus going with like a 650W power supply.

whenever he isn't doing any demanding efficiency is going to drop.

 

4 hours ago, _Hustler_One_ said:

Hello everyone..

I wonder if this statement is true or not. I've read (forgot which the source is) about PSUs that says, ~The highest point of "80+ Gold rated PSU" efficiency will be reached when its load is at around 50% of its rated power~ So for example a 80+ Gold 650W PSU will be at its highest efficiency at around 325W load.

Is this statement true?

It depends on the PSU because things like topology, components used, itc make a difference.

 

As a general rule the PSU is most efficient anywhere less than full load and under very little load it tends to be unefficient. 

 

If you want to know how to have the highest possible efficiency 

 

first figure out how much power you draw on the common tasks you perform and then choose a PSU that hits peak efficiency at that wattage and that's it.

 

Remember depending on how many hours your pc spends at idle or under load is going to make a difference.

 

You can use this to do the math about how much you are actually saving.

 

http://www.orionpsudb.com/efficiency-calculator

[Sakkura]

19 minutes ago, 17030644 said:

whenever he isn't doing any demanding efficiency is going to drop.

Yeah, but efficiency is more important when your system draws 350W than when it draws 80W.

[17030644]

Just now, Sakkura said:

Yeah, but efficiency is more important when your system draws 350W than when it draws 80W.

It depends on how many hours you spend at idle/load.

 

If you PSU is idling most of them time then NO

[Sakkura]

4 minutes ago, 17030644 said:

It depends on how many hours you spend at idle/load.

 

If you PSU is idling most of them time then NO

Every hour at high load counts much more than every hour at idle.

[17030644]

28 minutes ago, Sakkura said:

Every hour at high load counts much more than every hour at idle.

Yes i know that but if a pc is idling for like 10 hours and only 1 hour under load than load isn't really more important.

[Stefan Payne]

10 hours ago, _Hustler_One_ said:

Hello everyone..

I wonder if this statement is true or not. I've read (forgot which the source is) about PSUs that says, ~The highest point of "80+ Gold rated PSU" efficiency will be reached when its load is at around 50% of its rated power~ So for example a 80+ Gold 650W PSU will be at its highest efficiency at around 325W load.

Is this statement true?

no, it depends on the PSU; load and so on. You can't assume anything, you have to measure it.

You can try using the search and finding some postings of me where I debunked it a couple of times.

 

1) it depends on the PSU you talk about. Some are most efficient at 50%, but some are as low as 30% for example Cooler Master V550, most are around 40% or so.

2) If we are talking about 230VAC, the difference between 30 and 60 or 70% load is negligable. We are talking about less than halve a percent difference. 

 

 

So for you it makes more sense to get a good quality 550W PSU than a mediocre 650W.

[Stefan Payne]

9 hours ago, mariushm said:

my guess is they wanted to have a 450w, a 550w and a 650w model in the series ... so they probably use the same hardware as the 550w with maybe a lower size main capacitor

450W Bitfenix Formula has a whopping 390µF main capacitor...

Fr 450W I think a 270µF would be sufficient...