Reading all these threads about skew and gtl i want to advise some not to play with them if they want only to find a 24/7 setting.

Put 0.63x and 0.67x and skew to auto.
Then the voltages should all be set manually to lowest values
(nb,sb,pll,fsbt etc) and start raising only vcore,vmem and vnb when it is needed.
I managed 32m/3d Marks at 4500@Air with my current setup by only raising vcore,vmem and vnb.