Well just to clarify the ram doesnt have to increase in speed as your cpu is overclocked. With i7s there is a base clock this is how all of the components determine thier frequency. The cpu has its own multiplier and the ram has its own separate one also. As you overclock your cpu ur ram will increase in speed but u can set the ram multiplier lower to achieve a faster cpu overclock while keeping the ram at a lower frequency.
As far as making the 930 or 950 work with 1600 ram you do not need to change the speed of the cpu. All you would have to do is set the memory multiplier to a higher value until you hit 1600mhz. I used to run my i7 950 at stock speeds with my ram at 1600mhz but now i oc both of em lol