So I purchased a Antec 550 trio about a month ago and it has been working fine. This morning I turned on the computer and the PSU fan plus all five case fans didn't work. The videocard fan and cpu fan work fine. Here is my setup:
The quick guess is that the psu took a flier. If the psu fan was still working, I might suspect the motherboard, but since the psu fan is included, I think that wraps up the case. RMA the psu and try again.