Noobish Question - Re: PSUs & SFF Sys

[thorin]

I've recently been considering setting up a system based around Intel's new Small Form Factor board:
http://www.intel.com/products/mother...GLY2/index.htm

Which lead me to the following decent looking case:
http://www.ncix.com/products/index.p...facture=Apevia

Which has a 420W PSU. Does that imply it's drawing 420W all the time or that the max it can provide is 420W? Is there such a thing as under-loading a modern PSU? (ie: If I only have it loaded to say 40W ...... ~20W for D201GLY2 + a drive or two, will that be an issue?)

[streaker69]

I've recently been considering setting up a system based around Intel's new Small Form Factor board:
http://www.intel.com/products/mother...GLY2/index.htm

Which lead me to the following decent looking case:
http://www.ncix.com/products/index.p...facture=Apevia

Which has a 420W PSU. Does that imply it's drawing 420W all the time or that the max it can provide is 420W? Is there such a thing as under-loading a modern PSU? (ie: If I only have it loaded to say 40W ...... ~20W for D201GLY2 + a drive or two, will that be an issue?)

I believe that the 420W is the max that it can provide under 100% load. A good switching power supply should only supply the amount of current needed to run the current load. I believe that is the nature of a switching power supply.

I have seen some ATX PS's that will not turn on unless they have a some sort of drive attached as the motherboard does not draw enough current to trip the softswitch inside. Those were probably cheap PS's though.