550W vs 750W power consumption

[dumisoft]

Hello,
My PC has a Cooler Master 750W power supply.
I have only one graphics card. So, I know even 550W Power Supply is enough. My questions is, Without changing any part, If I put a 550W power supply, will it use lower electricity? I want to reduce my electricity bill. So, I want to know If I change the power supply to 550W without changing any other part, Will it reduce electricity bill?

In other way, If a PC wants 500W, and if we use 1000W, will it take more current?

Thanks

 

[Novuake]

THe ACTUAL power draw from the wall socket will only be the required wattage that your computer requires to run + the "extra" wattage required based on the efficiency factor.

For example 80% on a 1000w computer would have that PC draw 1200W from the wall to deliver the needed 1000w.

 

[dumisoft]

Thanks for the quick answer..
So, that means no matter if I use 550W or 750W, It will take the same current? (If we forget that "efficiency factor")

 

[TopLuca]

I just wanted to clear something out .

You need to be wary of idle loads , say your idle load is 100w and you use 1000W PSU the system will still be drawing power near to the 100W mark but efficiency at lower than 20% load isn't the greatest and PSUs are tested at 20% , 80% and 100% loads so that's why its not advised to grab something completely overkill however in your case everything is fine.

 

[Novuake]

Correct.

 

[4745454b]

To add what Top was talking about, you need to figure out how much you need, and what you normally draw. My PC tops draws ~325W. I use a 450W PSU. Yes, this is just north of 80% load. But most of my time is spent watching videos online and surfing. If I used a 600W+ unit so that the game load would be closer to 50% of the output, my "normal use" would be sub 20% then, and not as efficient as the unit I'm using. So you need a quality unit, one that is as efficient as you can, but can supply the power you need but not at the expense of everything else. Unless all you do is game with it.

 

[Novuake]

Over complicating things is a problem on this forum.

Not that they are wrong in mentioning it. Good to know, but not really helpful as the actual draw difference will be so little to not affect you in 10 years.

Unless of course you run a lot power hungry system.

 

[Rammy]

Some of the maths here is a bit dodgy but the sentiment is right - power supplies draw the wattage they need rather than drawing a fixed amount based on their capacity.

If you do want/need to reduce your electricity bills there are steps you can take but most of them do not yield big results, especially when you compare to the initial outlay.
These include -
Swapping components for more energy efficient ones.
Changing to a more efficient (and suited) PSU for the reasons mentioned by others.
Removing overclocks or actively underclocking components to reduce their power consumption.
Playing with power saving settings.
Using your PC less - not at all helpful but by far the biggest saver in practice.

 

[4745454b]

I wouldn't say the math is dodgy. I really tend to leave me computer running 24/7, and most of the time it's doing nothing. By using a lower wattage PSU, it spends most of the time being more efficient then if I got a 600W+. Everyone is different however so I was only trying to point out something else.

 

[TopLuca]

To be honest I found that all of the comments complete each other and build upon the same idea which is in this case to help the OP , all of the comments didn't have any dodgy math imo moreover I believe that the mod is trying to prove what he's saying by using a real life example so he's talking about himself to help the OP get a better understanding of the situation.

 

[Rammy]

I wasn't singling out anyone or picking up on anything particular, but a load of "napkin maths" can be a bit misleading.
Also 80% of 1200W is 960W, but that's really nothing.

My point, though poorly made, was that these kind of imaginary examples are useful for an explanation but not terribly helpful when you try to apply them.

 

[TopLuca]

Actually he meant 80% efficiency so it will draw 1200W from the wall to deliver 1000W to your system.

It's supposed to be 1.25 Kw to be of 80% efficiency , other wise it'll be of 83.33% efficiency .

 

[4745454b]

Also 80% of 1200W is 960W

Doesn't work that way. If he had done the math wrong I would have corrected him. If a PSU was 80% efficient at supplying 1kW, then it would be drawing 1200W from the wall. You lose 1/5th in efficiency. As I do the math I got 1250 draw, maybe I hit a button wrong. And 80% efficient PSU at 1000W doesn't mean 800W output, or any other lower number. It HAS to be larger then 1kW due to the loss.

 

[Novuake]

Look, ANSWERING the OPs question is the important thing, making it clear to understand is even more important.

The way I stated my answer was clearly a guesstimate to illustrate my point. I am sure he understood that little tidbit well.

 

[TopLuca]

I agree

 

[Rammy]

I wasn't making a big deal or nitpicking about questionable maths, it was an off the cuff remark, which is actually true - that not all of the maths in this thread is 100% legit. (if a fixed 80% efficiency PSU - which doesn't exist - draws 1000W then it'll draw 1250W at the wall. If it draws 1200W at the wall, the system is using 960W).
I 100% agree with the general points made, and I pointed that out in my first reply, as well as making a few vague suggestions about reducing power consumption.

I wasn't trying to undermine anyone's opinion, but to reinforce and add to it.