Ram runs at 1600 with stock CPU speed, but only mid 1300 when overcloc

[6POINT02E23]

Hi Guys,
I'm new to overclocking, so bare with me. I have i7 920 system with 6gig OZ 1600 ram. The memory runs fine @ 1600 but when I start overclocking the cpu I need to drop the multiplier to bring the memory into the mid 1300s.

So ram runs fine at 1600 with 920 at 2.66, ram only wants to run mid 1300 when 920 is overclocked to 3.6ghz.

Is this common?

 

[r_manic]

Could you specify your mobo and RAM? I suspect the mobo automatically scales down bus speed as you increase your CPU clock.