I'm doubtful there are any that much smaller and fanless. I know kingwin str-500 is basically the same size. You might have to mod yours.
there's something like this http://www.silentpcreview.com/Seasonic_SS-350TGM_Gold_TFX but obviously not fanless and is lower power than the one you have....but it is smaller
you might have to look at a sfx psu, they are smaller but i think have a noisier fan. something like this http://www.silverstonetek.com/product.php?pid=253&area=en
silverstone has other models they put in their sugo sugo5/6/7 cases but i'm not sure if you can buy them separate from the chasis
one that comes to mind is completely or partially removing the psu chasis. i've seen that done a couple times, but usually for extreme measures. i think there might also be higher risk of shock doing that