<< You just required to divide your acclaimed rating of assuming PC133 against standard 1000 which results as 7.5ns, hence for PC150, then it will be 1000/150=6.6ns, then if an PC166, it will be 1000/166=6ns. >>
Where did you get that info? From what I've seen there is no formula correlating the overclockability of the memory and the chip ratings. You can easily get a 64MB stick rated for 7.5ns and easily get over 150MHz @CAS2. You can't explain that with your math. There are also a lot of memory sticks sold as PC-150 with 7-7.5ns chips.