smallest, most silent PC fan out there

hey all,
my buddy is getting a closet grow ready in a 4' cab with lw at 3'x2' so a very confined space. first question is obviously what the smallest, most silent pc fan is at the moment. hes growing in a cab and plans on cutting holes in opposite ends of the box with the ducting installed according to the PC fan size (question 1). which leads to my second question. with the pc fan inside the ducting, could i cover the openings of the ducting with black clothes to prevent light leaks during 12/12? any pics/experience would really help. thanks alot guys

check these out: AC 115V Fans
... if you check their specs, they give the cfm and decibels of each model ... they also have lots of 12-volt computer fans, as well ... I have used one for almost 2 years ... no probs ... :smokin:

i looked there too for smaller fans

but you can also look at a Grainger Industrial Supply
if they are near. . i bought my 2 fans there and were pretty cheap. work good for my little veg cabinet