hs101

What I mean is: Lets say you have a 700 watt power supply and your entire computer build only needs to use about 400 watts, does the power supply only use arund that much power.

The reason why I'm asking this is because I don't want to end up pay extra monthly for the electricity bill for power that I don't use. I already have the 700 watt power supply.

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Clockadile Dundee

A 1000 watt power supply, with 100% efficiency, say at 10% load at 20c. At 20c, under a 100 watt load, it will use 100 watts.

So get the one with the highest efficiency. I will also mention that people typically vastly overrate the required wattage.

It is based on efficiency, and load; not maximum possible output, if I understand correctly.

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hs101

I think you misunderstood my question. I'm just asking whether power supplies are always running on their max wattage or do they use just as much as the computer requires.

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Afrodisiac

Just as much as the computer requires. No more.

Although, what Clockadile was explaining is relevant.

If your PC needs 300, your PSU uses 380 (79% efficiency). If it needs 400, it uses 480 (83%). If it needs 600, it uses 680 (88%). Meaning, the more power you demand from your power supply, the less it wastes.

(BTW, the numbers I used above are completely made up, just to give a rough idea of what I meant).

So, if you want to save on power, don't get an overkill PSU, since it will just be wasting power (like I show in my example above).

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hs101

So there is basically no drawback of buying a 1000w power supply vs a 500 watt power supply assumming they are both the same price, brand etc. Because I was hesitant to buy a power supply that uses way to much power.

Edit:what do you mean by wasting power?

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FearSC549

Depends on the efficiency of the PSU.

You use that much power just to play maple?

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Jtwizzle

Usually PSU's are most efficient at 40-60% load ranges, so if your PC draws 500W, a 1000W PSU will be ideal. Generally speaking.

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Afrodisiac

If I get a 500W PSU and use it to run a 300W rig, if I make up some numbers right now, 80% of the power drawn from your wall socket will go to your rig. Meaning your power supply will waste 20% of the power drawn from your wall socket.

Maybe 60% of the power drawn from your wall socket will go to your rig in the case of the 1000W PSU, since 300W is too low for the power supply to operate efficiently. In that case, 30% of the power drawn from your wall will be wasted, and since in both cases your rig only uses 300W, by getting a 1000W power supply you've just thrown 10% of the power drawn from the wall into the garbage.

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ZealotKi11er

This.

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urgrandpasdog

This. Though I would base it on what your rig draws in its most common state (ie, if it spends most of its time idling, by a PSU that does about double the wattage it takes at that level, and if your rig spends more time than not at load, buy for that).