Great job Dentnu! Yea, end of JN is a real good power draw and is where you'll first notice the grey screen phenomenon. I didn't think you'd be able to go much higher than 1.138 on air.
You're working your clocks real good. See what you can do on the CPU, then it will be time to water cool the gpu. Once you do that, it is likely that you'll be able to do 1000mhz on the core @ 1.213v. BTW, 940 (1880) is what I ended up with on air on my 580. You, me, John and a bunch of others got normal to lower clocking cards, while very few others lucked out and got cards to go close to 1100core/1200mem