See this thread:
http://www.silentpcreview.com/forums/vi ... hp?t=30289
So you've been testing with everything plugged in? As some others have suggested, try plugging in another 1 or 2 fans. Otherwise buy a psu tester like this: http://www.startech.com/Product/ItemDet ... EST20&c=US
It may be possible for DIYers to mod the device to use like in the examples discussed in the article above.
I have a similar setup but also with a wireless-G card, no sound card. I have a Zen 400 which requires a minimum starting load of 0.2 amps on the 12v line. I recall that the Silverstone Nightjar psu requires a minimum starting load of 0.5 amps and the Zen 300 is 1.0 amps. I specificially looked around for info on the minimum starting loads after experiencing some problems like you have.
I had similar problems with my Antec Neo430 psu (1.0 amp minimum starting load). It would not start when just connected to the motherboard. With the psu tester attached, the psu would start and the fan would sping. With all components attached it would start too, but I didn't try it at the time until after I read the above article.