RAM and PSU. Also anything you have access to, CPU, you could try the RAM in another mobo.
The Corsair support forum states that those use BH-5 chips. IIRC, they didn't have the built in voltage regulators (like the CH-5) so this made the BH-5 better for overclocking but not as good for stability, perhaps this also affects lifespan?
If you find out that it is the RAM causing the instability, you can at least make use of the Corsair lifetime warranty.
If you still can't get it stable after completely unclocking and removing all the power hungry components and have also eliminated the possibility of faults in each of the other components then RMA the board.