Power consumption of a psu

[barrymobiel]

hi,

My question is: if you have a system that uses like +-500 watt and you buy an psu of 700W, is your psu going to use less then 700w for your system or is it always going to use 700w
i want to put this in my pc:
Asus AM3 M4A89GTD PRO USB3 HDMI DVI VGA DDR3
AMD AM3 Phenom II X6 1055T 2.8GHz BOX
ASUS ATI 5850 Direct CU 1GB DDR5 voltage tweak ed.
Kingston DDR3 4GB 1333MHz (2x2GB) CL9
I know that antec tp-550 will do the job but i dont know how much noise it makes. If a psu of 700 watts does use less then 700w then im going to buy the cm 700w silent pro because i know that will quiet.

I'm a bit new with psu's.
I hope you guys can help me.

 

[Pyroflea]

Your system will only draw what the hardware requires. The size of the PSU does not effect how much power is drawn, kinda.

It also depends on the efficiency of the PSU; PSU's are more or less efficient at different loads, so that's the only way a larger PSU could effect the power drawn.

In your case, it will not draw 700w, but some number less than that.

 

[rolli59]

The power supply is going to use what ever load is on it divided by the efficiency if the load is 500watts and the efficiency is 80% it is going to use from the wall 500/0.8 = 625watts.