How much power?

[MerePeer]

How do I know how big a power supply is needed when building a new case?
Do you go by gut feel for the # of items being placed in the case, do you ?somehow? obtain wattage reqmts from each piece and add them up?
I like some microAtx cases but they have 250W supplies and I'm not sure how important to weigh that vs. a 300W supply.

TIA.

[IronBits]

You will really want a nice reliable 400 watt power supply for an AMD box with 'toys' ;)

[ECL]

If it's one of those really small systems like a Shuttle shoebox, it'll be difficult to get enough stuff in there to stress a 250W. If it's a grown-up box, I go for 350 or 400 watts.

[QIbHom]

Quality counts. An Antec 350 watt is better than a no-brand 400 (or even 450) watt. Go for an Antec or a Sparkle.

[Polski Radon]

FSP is another OEM company that creates great power supplies. The 350W FSP Aurora I bought has exactly the same electronics as the 400W Zelman PSU's, and is $20 cheaper.