Ive got my 6 270's running 700 watts or so now as well. take a look
How about posting a picture of your 6x270 rig? I'd love to see it!
Have you tested a voltage below 0.955? Mine have been rock solid there, and I'm interested in trying something lower. I'm going to test 1.038v on my XFX 280x's.
Cheers,
- VR