PSU Questions & Recs needed (along with case recs)

[OhNoPoPo]

I haven't built a rig for quite a few years now and it seems everything has gotten more complicated since way back when. My anticipated system:

Conroe X6600-6700-6800 (haven't decided yet, but I don't think the power draw is too different for each?)
2GB RAM
Audigy 2 Sound Card
2 Optical Drives
300-500GB HDD (not a raptor, obviously)
X1900 or 7800 video card (undecided...whatever is a good deal at the time)
TV Tuner

No OC'ing, no hard core gaming.

What realtively quiet PSU would you guys recommend?

That brings me to my follow-up question. Is the Wattage rating of a PSU its theoretical maximum or is it drawing that amount of power all the time? I don't want to get too high of a wattage rating if it's drawing that amount constantly.

Final question: thinking of the Lian Li V600 case, but it's pretty pricey...I like the slightly small form factor and the top mounted USB ports. Any alternatives?

Thanks!

 

[Zepper]

Switching PSUs draw from the wall relative to the load. The efficiency spec will give you an idea as to energy wasted as heat. Get an efficient PSU (the Seasonic S12 series was among the first high-efficiency PSUs) well matched to the load, so it operates in its peak efficiency zone (somewhere in to the 75-90% of max power output) and you won't be wasting a lot of energy. Most don't need more than a 450W PSU. The S12-380 is a good match for most - quiet and efficient.

.bh.

 

[OhNoPoPo]

Wow, thanks for that explanation. I never really understood that efficiency rating til now! So you think that setup will only require a 450W psu?