Well i think what he meant was that 4200U/4700U + GT750M/AMD 8850M will give overall more GAMING performance as compared to 3230M+740M. Since most games are not multicore optimised, the CPU performance MAY not(and i say may, bcoz I have not experienced it first hand) affect gaming that much
not really.... i have a y500 with a i7 3632 and 750m and i've run games in all possible clocks of my i7 and have noticed that when i clock my cpu low enough... it starts to bottleneck the 750! 750 is a very powerful card from i have seen... and you doo need a fast processor to complement it... else its a waste of money to go for such a card... (an i5 is more than enough to complement a 750m)
another thing is... while you're gaming... the cpu doesn't really know how much power is going to be required at t-->0+ sec... hence it cant really apply turbo boost efficiently... which makes it run at its base clock of the time. I'm pretty sure that a dual core running at 1.6ghz -2.0ghz cant utilize a 750m
however... if the end user starts using throttle stop.... then its a different story altogether! if throttlestop is used.... performance gain will be directly proportional to the difference in gpu capability of a 750m in respect to a 740m