PSU - 2x80mm fans, or 1x120mm fan?

I see many similar priced high quality Power supplies with either 2 x 80mm Fans, or a single big 120mm Fan over the CPU.

I figure the 1 x 120mm Fan leads to a quieter PSU (a big plus in my book), but how good is it at air ventilation compared to 2 x 80mm models?

It does of course depend on several factors. Design of the PSU case. The specs of the fan you are using. Specs of the PSU, etc.. The only thing that I can say for certain is that it will most certainly be quieter

yes examples will help. My Fortron has 1 80, and the air that is coming out of that thing warms my hands after I've been outside for a while in the cold. And my PSU that had a single 120mm vented not that warm air. So it really depends on the PSU. Post what you are looking at and we can give some guidance.

My Ultra X-Connect uses 2 80mm fans but adjust teh speed according to temp, and they run VERY quiet, unless you stick your ear next to them you don't hear em.

So I would say it's all a matter of design.

My Volt Modded Antec Truepower 430w only has a 80mm Panaflo L1A and it does fine. It is supposed to have a 92mm in there also. You need to search and see if the power supply dumps a lot of heat out.

ok, in particular, the OCZ Modstream 450W has one 120mm fan, and the Ultra 500W has 2x 80mm fans. i'm looking for something modular.

better yet, compared to those two i listed, which has better

- stability on rails
- air ventilation
- quietness

i'm also contemplating between these two Nikao PSU.

Nikao 450W Ice Power with 1x 120mm
http://www.btecanada.com/catalog/product_info.php?cPath=89_167&products_id=2448

Nikao 500W Alien Power with 2x 80mm
http://www.btecanada.com/catalog/product_info.php?cPath=89_167&products_id=2449

Only $10 difference between the two, but both are a good $30 or $40 Canadian cheaper than the OCZ or Ultra-X. I know no one has heard of Nikao PSU (absolutely zero reviews found in google), but they've been making pretty good cases for a while, and i think they are TopPower or BestPower brands, rebranded with LED lights. And the 12V rails are pretty tempting (35A for the 500W, 30A for the 450W). 2years warranty, not the 1 year as the website shows.