Power Supply Clarification

[ayeitsbagio]

Based on what I've read, a PSU will only draw what is needed depending on the components and the PSU.

I have a PSU of 520w made by sea sonic and currently my PC draws about 200w. So If I'm correct, since the draw is only about about 38.5%, the PSU will only draw 200w correct?

However, if my PC needed about 420w(81%) of that 520w, it will need an extra 10% making it draw 472w? If I'm totally wrong, can someone please explain? Thank you very much

Edit: PSU is 80+ Bronze SeaSonic m12II Evo Edition
-Super High Efficiency (up to 87%)

 

[jankerson]

Yes, they will only supply the power that is needed or asked of it by the machine.

 

[Kasper Jorgensen]

Your PSU will draw what your computer needs plus more added depending of the efficiency of the PSU.
So, if for example your computer needs 200w and your PSU has 80% efficiency at that load it will draw 200/80*100 = 250w from the mains.

 

[jankerson]

That will depend a lot on the exact model of PSU however, the top end models are much more efficient, well into the 90's depending on the exact PSU models.

 

[Kasper Jorgensen]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

 

[Rexper]

The psu will deliver the power that is required, but take that times the efficiency of the PSU.

PSUs do not perfectly convert AC energy to DC energy, they lose energy along the way for example as heat. Because of thos, PSUs need to take a bit more from the wall to deliver a certain amount.

For example, if your PSUs is tested to have an efficiency of 86% at a 200w load. It would draw (200 / 0.86) ~233 in order to deliver 200w for the parts.

A power supply with a max rated of 550w, with 80% efficiency can deliver the 550w to components, but draw 687.5w from the wall in order to compensate for the energy loss in conversion.

 

[ko888]

Efficiency also varies with input voltage:

 

[jankerson]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

For most games I can't even hear my system running unless I get really close.

Games like GTA V and Rise Of the Tomb Raider.

 

[Kasper Jorgensen]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

For most games I can't even hear my system running unless I get really close.

Games like GTA V and Rise Of the Tomb Raider.

Not sure what your noise level has to do with this mate?

 

[ayeitsbagio]

Thank you for the input everyone! It's getting clearer now with all your explanations

 

[Kasper Jorgensen]

Efficiency also varies with input voltage:

Yes that is quite obvious as a lower voltage will need a higher current to deliver same wattage, and with a higher current you will get a higher voltage drop. But this also shows what i said above, that they are most efficient in the middle range of their rated load.

 

[ayeitsbagio]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

Yeah I did more research prior to choosing a PSU and was about to purchase a corsair CM series which was a terrible idea and decided to grab this brand since seasonic is well known to be reliable.

 

[jankerson]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

For most games I can't even hear my system running unless I get really close.

Games like GTA V and Rise Of the Tomb Raider.

Not sure what your noise level has to do with this mate?

If the PSU is underpowered it will heat up and the fan will start making noticeable noise normally.

But then that depends on the PSU and system specs etc.

 

[Kasper Jorgensen]

Yes, one should never cheap out on the quality of the PSU, but is for other reasons as well. However, most PSU will be most efficient in the middle range of their rated load, usually somewhere in the 40-60% range. So you need to consider if paying more upfront for a larger PSU and possible a higher efficiency rated one, would pay itself of by reduced electricity bills. Obviously that depends a lot on where you live and how much electricity cost in your country.

For most games I can't even hear my system running unless I get really close.

Games like GTA V and Rise Of the Tomb Raider.

Not sure what your noise level has to do with this mate?

If the PSU is underpowered it will heat up and the fan will start making noticeable noise normally.

But then that depends on the PSU and system specs etc.

Still don't get what that has to do with anything, and how can a PSU be underpowered?