Some of those are Flex-ATX power supplies, which are quite different from TFX.
Flex-ATX - 6" x 3.25" x 1.5"
TFX - 7"x3.4"x2.5"http://www.directron.com/matxps.html
That's a big height difference when squeezing them in on their sides into the 'mini desktop' cases. There is a good review of a new 250W 'flex' form Seasonic here - http://www.xbitlabs.com/articles/cases/ ... html#sect0
. Perhaps it would be a good alternative to fit in all those low-profile cases.
And others take a micro-atx PS, which is different again: 146mm x 126mm x 74mm (5 3/4" x 5" x 3") with the fan sitting on top. The new Lian-Li Q09FN appears to take a micro-ATX form.
There are, at least 4, very different, non full size ATX, forms. It seems to me that many of the case specs don't tell you which 'small' PS they actually take!