I've been having similar boot issues. I found this other thread which says that the PSU is having issues detecting enough power draw on boot. I stuffed a PCI card in (WinTV PVR-250) and that seemed to do the trick. I wish Corsair would just come up with a more elegant solution though, since I can't actually fit that card in the low-profile case.http://forums.bit-tech.net/showthread.php?t=214538
...this is an issue with corsair CX psu's at the moment.
Basically the load is so low on start up that the psu believes nothing is connected and the psu shuts down.
You can test this by putting in a dedicated graphics card and then the system will boot.
Corsair are currently working on the issue and believe it to be a Llano issue and not a motherboard vendor specific problem.