Question about PSU and electricity

[Jerry000]

Is there any difference in electricity usage between these two:
http://www.mindfactory.de/product_info.php/550-Watt-XFX-TS-Series-Non-Modular-80--Gold_949421.html
http://www.mindfactory.de/product_info.php/650-Watt-XFX-TS-Series-Non-Modular-80--Gold_952828.html

One is 550W and other 650W. Do they use same electricity? I mean...if one is 650W and my PC needs 300W, what happens with other 350W?

 

[Darkbreeze]

You hardware uses what it needs, period. The PSU does not MAKE the electricity, it simply converts it from AC to DC, regulates it and provides it to your hardware in the capacity needed as demanded by the current load. It will only use what it needs.

A power supply only puts out as much power as needed by the system's components. In some cases, an 800W power supply may actually use less power from the wall than a 500W power supply, depending on the efficiency of the units. Often times, buying an "oversized" PSU is a good choice due to it's ability to perform even under higher temperatures, a quieter fan because the unit is delivering a lower percentage of it's total capability and considerable system upgradability without having to worry about having enough power when upgrading a graphics card, adding a graphics card for SLI or additional hard drives.

 

[fredfinks]

its not drawn from the wall. The 650w is basically how much power it can distribute.

What makes the difference with PSUs, apart from quality of components and reliability, is efficiency. i.e. bronze, silver, gold, etc ratings.
No PSU is 100% efficient. The higher the efficiency, the less power drawn from the wall to provide the power. Thats where power is lost - in the form of heat.

 

[Jerry000]

So, this one 650 its a smarter choice? And both are gold
http://www.mindfactory.de/product_info.php/650-Watt-XFX-TS-Series-Non-Modular-80--Gold_952828.html

Its cheaper than 550 now, so i think what you say, this is a better choice

 

[Darkbreeze]

That XFX unit is made by Seasonic. It's a good choice. If the 650w is less expensive, then go for that as it's likely to run quieter, cooler and last longer, plus, you'll have room for upgrades to just about any single GPU card you desire.