[SOLVED] How PSU Work

[DiabloDizzy]

Hello again,

So, in local forum, i have some hot debate with other member about how psu work.
I believe that the psu supplies ENOUGH power depending on the components and workload.
But he said it doesn't, he said the psu without 80+ efficiency draw maximum power even on idle system.

Then i think again, is it true?
I thought the psu supplied needed power even with the worst psu

 

[Deleted member 362816]

Lots of self proclaimed power supply experts on toms. I am sure you will get many answers.

Power supplies do not draw maximum power at idle unless you were powering a system that pulled 300 watts at idle and were using a 300-350 watt power supply.

https://www.velocitymicro.com/blog/... Plus is a certification,of 625W at 100% load.

 

[John Chesterfield]

You are correct, your local forum don't know what they're talking about. A power supply will only provide what is asked of it.

 

[JWNoctis]

Ask them how they came to that conclusion; It might make an interesting read.

But yes, almost all modern PSUs would only draw what they are asked of, plus what their own cooling fan and controller consume, plus other inefficiencies mostly proportional to output power.

The fact that even the worst power supply won't make a fine space heater at idle should have twigged them. But alas, no.

 

[jayjr1105]

I wonder how many people think that if you buy a 850w power supply that the PC will use 850w regardless of the PC's load.

 

[DSzymborski]

That being said, anything being sold in 2021 that doesn't have 80 Plus certification is almost certainly junk for reasons other than efficiency, and shouldn't be used on any PC that has parts worth protecting.

 

[Grobe]

The way power supplies work may be too much to explain if the recipient doesn't know basic electricity concepts.

So here is another approach.

Say you have a car. The engine have a maximum of 200 horsepower, making it a fast car.

Then you drive on a highway, say speed limit are 80km/t. During this drive, you don't push the engine to the maximum, but instead you less the throttle as the speedometer get closer to the speed mark.

Kind of the same concept when it comes to power supplies (on a very rude comparison model).

 

[jayjr1105]

That being said, anything being sold in 2021 that doesn't have 80 Plus certification is almost certainly junk for reasons other than efficiency, and shouldn't be used on any PC that has parts worth protecting.

Double Forward Group regulated units can still be 80+ rated. This is not an identifier of quality.