No I didn't use nTimings yet.Need little time to study datasheet and settings.
From what zakelwe says,I came to the conclusion that my memory is crap -at least compared to others.
Not really crap if it can do 700 instead of 550 but is not enogh for this card.
From what I know,timmings for 6600nonGT are the fastest in the 6serie.
I would not go for slower timings,because is not possible to overclock more anyway.I would go for faster timings to improve performance at same speed clock.But this need to be studyed.
By the way -did you do the mem voltmod? What is your max clock artifact free?And tell me if you use any heatsinks.