Overclock List:
DDR2-800 4-4-4-12 1.9v 1T (2.40GHz 1.25v)
DDR2-800 4-4-4-12 1.9v 2T (2.40GHz 1.25v)
DDR2-900 4-4-3-12 2.1v 2T (2.70GHZ, 1.45v)
DDR2-920 4-4-4-12 2.1v 2T (2.76GHz, 1.35v)
DDR2-1000 4-4-4-12 2.3v 2T (2.500GHZ, 1.4v)
DDR2-1100 5-5-5-15 2.45v 2T (2.75GHz, 1.45v)
DDR2-1100 4-4-4-15 2.40v 2T (2.75GHz, 1.45v) (95% Stable)
DDR2-1140 5-5-5-15 2.4v 2T (2.85GHz, 1.45v)
When I benchmark, I admit I don't make much sense. I am one of those people who don't pay much attention to voltage.. and when I increase it I rarely decrease it. For 1066, I would imagine 2.3v would be more than enough if you want CL5. Probably 2.45~ for CL4.