What device number was it listing in cgminer when it stopped?
I didn't catch that unfortunately.
I know you said you have good cooling on it, so its most likely not a overheating issue. Can you try unplugging it for an hour or so and see if it works after that? just give it a nice rest to discharge and reset all the vcore strings.
it sounds strange, but does correct the issue some times.
I just tried it again and CGMiner flashed ZOMBIE. Then found 0 chips. Both lights are illuminated. Other 3 are humming away.