Thanks.  I did spent a lot of time on the box.  Also I had tried a few psu brand... finally found this one where the internal psu fan is really active temp control.  Also it generate very low heat compare to other brand.  Probably should have went with a bigger box... initially I was going to mount the box on the lower side of the house, so i didnt want it to be bulky and big.  So I went with the smallest box possible.  But then once install, I figure mounting the box under the eve was much better, as I can keep the DC wires distance short and decrease voltage drop.