3x 6970 ASUS DirectCU II's pull 800 Watts... so 1000w is a bit on the low side...
Interestingly after 5 hours of troubleshooting...i came to the conclusion that 3xASUS directCU II will not under any circumstance work together... one always dies with ATI Driver Error.. .Tested each individually... they all work, just not together... it's a strange world i tell you.
Make sure they aren't crossfired.