About the power supply

[nihilite]

Can I get a 750watt psu if my system only require 400 at the moment because I dont have a power supply but plan on upgrading my HD 5670 to a 5770 then crossfiring a little after that.

 

[JackNaylorPE]

A 750 watt PSU will operate at close to peak efficiency w/ a 400 watt load. I would note however that the 650 and 850 watters are the sweet spot for PSU's price wise.

This 850 watter is a top end (10.0 performance rating on jonnyguru) and is only $109 .... the 750watter is $20 more !
http://www.newegg.com/Product/Product.aspx?Item=N82E16817207001

Twin 5770's require only a 600 watt PSU however
http://www.amd.com/us/products/desktop/graphics/ati-radeon-hd-5000/hd-5770/Pages/ati-radeon-hd-5770-overview.aspx#3


in which case this 650 watter will do just fine

http://www.newegg.com/Product/Product.aspx?Item=N82E16817371015

 

[nihilite]

Could you (or anyone else) explain what peak efficiency means psu wise? I read somewhere that its good to have 200w extra over head room.

Kinda dumb but would a 850 watt draw 850 watts from the wall? Or only how much is required.

 

[nihilite]

Best answer selected by Nihilite.