PSU Consumption question

[Joeychgo]

I think I know the answer, but I wanted to ask anyway to be sure.

 

 

Lets say I only need a 600 watt PSU.  But I decide to go for overkill just in case I decide to expand or whatever, and buy a 1000 watt psu.

 

Will it actually consume any more electricity?  Or will it just consume what it needs to run the system at the time regardless of what the watt rating of the psu?

[cnapier39428]

Power supplies have a "sweet spot" so let's say your system consumes 550w, that 600w PSU is having to work hard to supply that where the 1000 is barely sweating and more efficient because of that so the 1000 would use less power because it can deliver 550w more efficient

[Joeychgo]

so bigger is always better, price and psu quality aside?

[Oshino Shinobu]

It will consume whatever the system needs. And also what @cnapier39428 said. 

[Oshino Shinobu]

so bigger is always better, price and psu quality aside?

No. You'd be better off going with a good quality 600W than a bad/okay 1000w for example. The amount of energy you'll save is not worth the extra cost. 

[Wano97]

I think I know the answer, but I wanted to ask anyway to be sure.

 

 

Lets say I only need a 600 watt PSU.  But I decide to go for overkill just in case I decide to expand or whatever, and buy a 1000 watt psu.

 

Will it actually consume any more electricity?  Or will it just consume what it needs to run the system at the time regardless of what the watt rating of the psu?

It won't consume more

[helping]

 The amount of energy you'll save is not worth the extra cost. 

What do you mean?

 

If they're both quality units, the 1000w is likely to consume more power for the same output. 

[Oshino Shinobu]

What do you mean?

 

If they're both quality units, the 1000w is likely to consume more power for the same output. 

Was sort of going off the first post made. 

 

Either way, I would recommend getting a good quality, lower wattage PSU, rather than going overkill. 

[JAKEBAB]

Power supplies have a "sweet spot" so let's say your system consumes 550w, that 600w PSU is having to work hard to supply that where the 1000 is barely sweating and more efficient because of that so the 1000 would use less power because it can deliver 550w more efficient

your so wrong power supplies are most efficient at 80% load so if u are using 1000w for a 550w build that is terrible efficiency! 

[Joeychgo]

Yes, assume I buy a good quality PSU ---    If cost isnt a factor - does it matter if I go overkill as far as electric usage or will the system draw what it needs regardless of the psu wattage?

[helping]

What @iSeako and @cnapier39428 are trying to say is, that you are looking for good quality and with the right "sweet spot"

I'm sorry for the wrong terminology, since I don't really know the right words in english and google gives me a hand full of options.

 

You have 3 kinds of power:

1. Total Power

2. Real Power

3. Wattless Power

 

let's work with a 1000W PSU for this example.

We assume, that it is on a 80% load so we are using 800W of total power.

Now what is real and wattless power? Easiest eplaination is actually:

real + wattless = total

Imagine a glass of good drawed beer in germany with a good crown of foam on the top.

The yellowish substance we see is the beer itself what makes us tipsy and the foam is there as well, but it has basically no effect on us. So the beer is the real power and the foam the wattless power.

The same effect occurs in PSUs. So we are running it at 80% load = 800W and we have a 90% efficiency. 90% of 800W is 720W.

So we get 720W of real power... the other 80W is just wasted by heat output or smth.

All the newer PSUs have a efficiency graph on the side of the package. Just check it out and see if you can get the right PSU.

If you are going to upgrade your system with other components in future, go for a bigger one from the beginning. but always keep that efficiency thing in mind if you want to have it perfect.

Check out my rig in my profil and my PSU is actually an overkill one. But I'll get some watercooling with two circuits and a quadro card someday.

And it will stay overkill, cause while buying it i havent thought, that I won't use all components all at once!

 

You're right, but just to make it clear, power demand(P) and real watts= P/efficiency (variable by load) 

 

A PC that requires 500w with a PSU 80% efficient at 500w power demand will draw 625w+ from the wall. 

 

The key difference is some may get confused with what you said, interpreting that literally would mean that a 80% efficient 1000w PSU would only power up to 800w at full draw, where as it should provide up to full declared wattage but at 1000/.8w consumption from the wall.  

[Joeychgo]

Well, you guys have completely missed the point of my question.  let me try again...

 

 

Lets say my machine needs 430 watts to run at load.       I could get a 550 watt PSU and run just fine.  But, if I get a 1000 watt PSU, will I draw more electricity then if I just had the 550?   (under the same 430 load)

[helping]

Well, you guys have completely missed the point of my question.  let me try again...

 

 

Lets say my machine needs 430 watts to run at load.       I could get a 550 watt PSU and run just fine.  But, if I get a 1000 watt PSU, will I draw more electricity then if I just had the 550?   (under the same 430 load)

No, your questions were answered. You didn't read the thread. 

[Joeychgo]

Its a little hard with all the technical talk --- wattless power -- 80% load and 90% efficiency.   I was seeking a basic yes or no with maybe a little explanation that someone who isn't a full blown techno geek would understand.. 

[helping]

Its a little hard with all the technical talk --- wattless power -- 80% load and 90% efficiency.   I was seeking a basic yes or no with maybe a little explanation that someone who isn't a full blown techno geek would understand.. 

If both PSU's had the same quality and similar efficiency curves then the 550w would consume less power at 430w load than the 1000w PSU.   

 

the difference is still marginal 

[Joeychgo]

the difference is still marginal 

 

THAT is what I was looking for.   Thank you.

[Ganthos]

The post answered a lot of questions I had but kept forgetting to ask.