Do all PSUs have Peak Power?

[phongle123]

I was looking at the Dark Power Pro 11 1200W and it says it has a constant of 1200W and a peak of 1300W.

Do all PSUs have a peak wattage over their constant? How would I find out what the peak Wattage would be?

 

Also, how would I find out if how much power from the wall the PSU would pull to be able to reach the 1200W of the Dark Power Pro 11 1200W if the efficiency is for example 90%?

[seon123]

All PSUs that aren't absolute garbage (and ma y that are) have a peak wattage above the continuous rating. Think 10%. 

Extremely basic maths tells us that 1200W/90% = 1330W. 

 

Why are you even considering a 1200W PSU, and why do you care about how much the PSU can draw from the wall?

[phongle123]

11 minutes ago, seon123 said:

All PSUs that aren't absolute garbage (and ma y that are) have a peak wattage above the continuous rating. Think 10%. 

Extremely basic maths tells us that 1200W/90% = 1330W. 

 

Why are you even considering a 1200W PSU, and why do you care about how much the PSU can draw from the wall?

1

So from the wall if it's 90% efficient then its 1200/.90=1333W with a peak of 1300/.90=1444W?

[mariushm]

No.

 

The power supply can provide as much power to devices as the label says. If the label says 1200w, then that means up to 1200w can be safely given to components.

 

Of course, the manufacturer designed the power supply with some margins, it won't simply shut down if the devices in your computer take 1201 watts from the power supply - there is some small amount above the 1200w threshold but it's not a guaranteed amount. Usually, it's around 10%, but you can't rely on that. 

 

The efficiency means just that, what percentage of the total amount taken from the outlet is actually sent to devices in your computer - the remainder is wasted in the form of heat.

If the power supply gives 1200 watts to devices and does that with 90% efficiency, you can use the most basic formula you learned in school to calculate how much power it takes from the outlet :

 

90% ..... 1200w

100% ..... ? w 

 

?  = 1200w x 100% / 90% =  1333 watts.

 

In most countries, the maximum amount of power that can be safely taken from an outlet is limited by the fuses in the house. In some countries the fuse is 15A, in others it's 16A ... so for example in US you may have 110v 15A  outlet ... but the manufacturer of the power supply can't be 100% certain you're always going to have 110v, depending on where the person lives the voltage may go as low as 100v during some times of day... So 100v x 15A = 1500 watts.

 

 

I'm saying this because there are some power supplies (like for example 1600W models or server power supplies) which advertise a higher maximum output when running on 230v compared to running on 110v - on 230v, the power supply can take up to 230vx15-16A = 3000+ watts

 

Note that the efficiency of a power supply is not constant over its output.

Here's for example the efficiency of a Dark Power Pro 11 1000w model, when running on 230v AC - with 110v assume about 1-2% efficiency drop at all points in the graph:

 

 

So your 1200w power supply may be up to 92% efficient at around 700-800w, but it will slowly go down to maybe 89-90% at the maximum output of 1200w

 

[phongle123]

31 minutes ago, mariushm said:

 

 

I understand that efficiency goes down. However, my OP stated for it to reach the full 1200W with the 90% efficiency as the example. Which you answered along with seon123. So I guess the peak wattage will have to be something I have to find from the manufacturer or a reviewer.

 

This post was not about the Dark Power Pro 11 PSU it was just in general. The Dark Power Pro 11 was one of the PSUs that I found that stated a peak wattage. So I used it as a comparison.

[OrionFOTL]

51 minutes ago, phongle123 said:

So I guess the peak wattage will have to be something I have to find from the manufacturer or a reviewer.

Why do you want to find it out?