PSU won't boot the motherboard!!!?

Try running a single stick of RAM to see if it boots up.
Or test a different module altogether... perhaps there is an issue with the memory.

The RAM sticks are functioning perfectly. "Still no solution in sight."

I’ve been going through this entire thread again, and here’s my take:

1. The motherboard works fine with the MS power supply.
2. Corsair works with other boards.

Ergo, the only possible culprit for incompatibility is the connectors. Take a close look at the voltage connectors plugging into the board (the 24-pin and 4-pin). Check if any wire has slipped out of the terminal, causing a loose or intermittent connection. Also, inspect the headers on the motherboard itself to make sure there isn't any debris inside. Check how they seat when you plug them in—make sure nothing is obstructing them and causing one end of the connector to sit unevenly or hang loose.

If it’s not that, then I’m stumped doing this remotely. At that point, I’d probably be doing what Antony suggested and grabbing a multimeter to test the actual voltages...