My friend and I are discussing PSU draw and we cannot figure out if a server with 2 or more PSUs (redundant power supplies basically) draw the full amount of power they are rated for on both, or if while both are running they share the load equally.

We cannot find any solid documentation on it. Can anyone help me locate this information?

We are researching this to properly estimate power consumption for a UPS.

To my knowledge, the computer only draws as much power as it needs from the psu (90 watts for example)and if two or more are present the load is equally dispersed. The psu hardly ever outputs the full load they are rated for. Most of the documentation I have come across is on forums similar to this one. Hopefully that helps

Thank you for your reply. We did find the information we were looking for, even if we didn't find any hard documentation, the load balance seems to be fairly standard.

So when building a server with redundant power supplies, 1 power supply must be able to handle the maximum draw of the server, but they will load balance and they only draw what the server draws.

Which means (from what I can tell) your desktop computer at home only draws what it needs (or should in theory anyway).

yes your desktop at home would basicly do the same, it will only draw the power it needs from the psu, thus when the load get higher then the power consumption get higher

A UPS (Uninterruptable Power Supply) is not the same as a PSU (Power Supply Unit). A UPS is used in case of a power outage. It will give you about 5 minutes of power so you can save and close applications and shutdown safely.
The PSU provides power to the computer. There is no extended power if your mains pwer turns off.

A UPS (Uninterruptable Power Supply) is not the same as a PSU (Power Supply Unit). A UPS is used in case of a power outage. It will give you about 5 minutes of power so you can save and close applications and shutdown safely.
The PSU provides power to the computer. There is no extended power if your mains pwer turns off.

Right, but we weren't talking about that. We were discussing how much draw is placed on the psu.

Sorry, it was 3am and I was looking at it cross-eyed.

Okay, it's only 830pm now so hopefully I can be more concise.
I am not a technical person so bear with me.

Every component draws power - PSU (12volt fan and circuits), system fan, cpu, cpu fan, mainboard, ram, video card, hard drive/s, thingies attached to ports (like mobile phone, mp3 player, Ipod), modem, anything that is plugged in, draws power.

A cd/dvd mulit-burner draws more power than a cd-rom or dvd-rom.
A cd/dvd multi burner draws more power when burning and even more power to burn at a higher speed.

You will notice a power drain on some components when you use a particular to component to its upper levels. You notice a slowdown when testing programs you have just created. This draws power from the cpu.

if you calculate the watts or amps of all of the plug and play things, you will find that online calculators do not account for the extras.

Current computers require a minimum of 550 watts or 28 Amps. to ensure good power useageI I recommend 600 to 750 watts for the super-dooper computers with all the latest gadgets.

If the power supply is way over the top. for example, 600 watts on a Pentium 2 then, you may have over charge on your account and may frack the mainboard.

I hope this has been some help. Good luck finding any site that provides the power consumption of components. At best all I could find was a P4 mainboard averaged 135 watts.

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