How much power does a 680W PSU actually use?

[orion23]

Hi,
I have a 680W PS and would like to know what this means in terms of my electric bill.

How much power does it actually draw? (can it be compared to a fridge, AC unit)

I went from a 350W to a 680W and would like to know how much more in the electric bill I'm looking to pay now!

TIA!

 

[LED]

It depends on the Hardware that is hooked up and running plus each PSU make has different draws...

 

[wanderer27]

I've always heard that other than what it takes to idle, that a PSU only draws what's asked of it by the MB and Devices.

The extra power is there if you have spike demands, or for example when going into gaming and your Graphics Card really starts to kick in.

Maybe someone else can verify this. I think there's also a thread around here somewhere about this too.

 

[WhipperSnapper]

This is an excellent question and an often and easily overlooked issue. What will my electric bill be ???

Here's an interesting question--would the added electricity cost of having two cards in SLI make SLI less economical than just purchasing a single powerful card?

 

[wanderer27]

Depends on the Cards. I think the 7800 GTX's run about 250-280 Watts, so that's about like having 3 - 100Watt Bulbs running for each Card.

 

[DigitalFreak]

If I remember correctly, if you buy a power supply that is much larger than what you actually use, you end up wasting electricity. Don't know how much, but it's probably minimal.

 

[vanvock]

Originally posted by: DigitalFreak
If I remember correctly, if you buy a power supply that is much larger than what you actually use, you end up wasting electricity. Don't know how much, but it's probably minimal.

No, not really. The supply rating refers to what it is capable of suppling, it doesn't put out that much constantly unless the hardware hooked to it requires it. They have an efficiency rating that relates to how much power is lost as heat in the conversion process. You want one with a rating of at least 70%. The higher the better. If the 680 has a better eff. rating & you have the same hardware you'll probably pay less.

 

[tcsenter]

How much power does a 680W PSU actually use?

The same power that a 400W or 500W PSU would use, given the same components and usage, and the same power factor correction type (passive, active, none).

Your components use power, not your PSU (minus cooling fans and internal circuitry). The PSU supplies it.

 

[L00PY]

Originally posted by: vanvock
No, not really. The supply rating refers to what it is capable of suppling, it doesn't put out that much constantly unless the hardware hooked to it requires it. They have an efficiency rating that relates to how much power is lost as heat in the conversion process.

Ah, but the efficiency isn't constant across the entire load -- it's a curve, usually peaking at around 60% of max rated load. A 680W PSU probably doesn't hit its peak efficiency until around 400W or so. If your system only uses half that amount, you will be getting lower efficiency than a 350W PSU that is comparable efficiency wise.

That is, if both PSUs claim 80% efficiency, under a 200W load, you might be very close to that 80% with a 350W PSU but only reaching 75% efficiency with that 680W PSU. That difference in efficiency is probably on the order of $0.60 difference a month running 24/7 at around $0.05 per KWH.