# [SOLVED]If a Power Supply is 750 watts, does that mean you pull 750 watts of power also from the wall?

#### Iver Hicarte

##### Honorable
Title says it, if a power supply is a 750, 950 or 1000 watt power supply, does that mean it pulls out that much power from the wall? To my knowledge I think it's not (correct me if I'm wrong) but if it doesn't then, how much power does a computer usually pull out from the wall?

Solution
No. It's just the maximum output it can handle. It's like the max speed on your car. A new Corvette can go up to 194 mph, but it doesn't go 194 mph all the time, just when you want it to.

If PSUs drew that much wattage all the time, everybody who owned one would be poor and their office would be a sauna. Because all that draw would become heat.

#### DSzymborski

##### Titan
Moderator
No. It's just the maximum output it can handle. It's like the max speed on your car. A new Corvette can go up to 194 mph, but it doesn't go 194 mph all the time, just when you want it to.

If PSUs drew that much wattage all the time, everybody who owned one would be poor and their office would be a sauna. Because all that draw would become heat.

#### TerryLaze

##### Champion
If the system draws the maximum that the PSU offers, then the PSU draws more than what it is rated for, that's the efficiency rating of the PSU, a 90% PSU will draw 10% more power than rated a 80% will draw 20% more power.

That's also happening at any power draw, some amount of loss is always there.

Also I think the efficiency rating of PSUs is not at max power draw but at a point the manufacturer chooses but I'm not completely sure about that.

Iver Hicarte

#### itrip

##### Reputable
I have two computers with a 1000Watt PSU, and they don't draw that as much power as they are rated for, only what they use.

Having a higher power PSU than what you need gives your entire system that much more headroom.

My entire household only uses 10Kwh per day, on average.

Iver Hicarte

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