Burnin did some OC tests already and it looks like you'll need 1.34V to run at 450Mhz.
https://bitcointalk.org/index.php?topic=179769.msg2745262#msg2745262And i have some numbers to go with those from yesterday:
Slightly different air cooling setup therefore different temperatures with air cooling. (fan placement)
TL;DL : 450Mhz [9Ghash/s] - STABLE
But at the cost of 94Watts of power.
Air:
431 - 54, 48, 1.30V, 87W, stable
450 - 56, 48, 1.30V, 90W, HW Errors
450 - 57, 52, 1.34V, 94W, slightly increased error rate compared to what i normally call "stable" but close enough
Water:
450 - 54, 32, 1.34V, 94W, slightly less hw errors then with air
I know, but when i would test out the real limits i would lose not a few money. Burnin has the possibility to do this for a low price and when we donate for this test he maybe is willing to do it. Of course he would need a recompiled cgminer then.