I have a 350W Cooler Master PSU. Does this mean I'm consuming 350W of power?

slicksilver

Golden Member
Mar 14, 2000
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at all times? or it the max? I ask this for sizing my battery for my UPS. The only two items that will be connected are the Monitor and the PSU to the UPS.
 

lehtv

Elite Member
Dec 8, 2010
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No, it is a Power Supply Unit, so it supplies power. It doesn't use power, it converts AC power from the wall socket to DC power for the components. It's the components in your PC that use power, the PSU only supplies as much as is needed at any given time.

Regarding UPS choice, I think it's a good idea to get one that is capable of the maximum load on the PSU plus whatever peripherals you need to connect to it. About 400W would be good
 
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mikeymikec

Lifer
May 19, 2011
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lehtv's response is generally correct, though PSUs do use power in a way, hence the power efficiency ratings such as 80+ for PSUs. I'm pointing this out because obviously the OP doesn't know much about PSUs, no offence, and a good quality PSU is pretty important and is worth reading up about.

As for the UPS, I would first suggest buying a load meter of some description to find out the power usage of your computer equipment (under idle and load) and pick a UPS based on the results and your requirements (do you want to continue working for some length of time when only UPS power is available, or do you want to shut down safely, for example).

I have a Corsair VX450 PSU, the maximum load I've monitored of my PC's tower is 186W IIRC (during gaming).
 
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lehtv

Elite Member
Dec 8, 2010
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Converting power is a more accurate term than using power. The only reason power flows through the PSU is if there are other components that require powering. The PSU itself hence does not use power, it converts AC in to DC + waste heat.
 

Torn Mind

Lifer
Nov 25, 2012
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An extension cord plugged into the wall uses no "power', or more accurately, has practially no current flowing through it, when nothing is connected to it.

A wall wart power supply (merely a different design, but it still converts AC current to DC current), likewise, has practically no current flowing through when nothing is flowing through it.

The same applies to power supplies in computers. It is the components that demand electricity when needed.

Wattage can be derived by multiplying voltage by amperes. Amps can vary waaaay more than voltage(voltage must stay within a tight margin) and is the variable you need to look at when determining watts.
 
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infoiltrator

Senior member
Feb 9, 2011
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The points to remember are most computers spend much af their time at idle or near it, and power supply efficiency at maximum load. IE, A 350 WATT power supply at max load and 80% efficiency is drawing 420 watts from the "wall."