I am not sure that this question even makes sense. I do NOT want to OC my CPU right now, various reasons, however I'd like to get the max performance from my memory. I've read somewhere that memory runs at a stock speed unless otherwise set, and that speed is not 1600. The memory I have:
Overclocking memory has almost no benefit at all in any real application but if you want to do it set the speed and voltage to there stock settings in the bios and try to see how low you can lower the timings. You could try increasing the multiplier and raising the timings. You suggest you may be overclocking the CPU at a later date if you are I would leave the memory at its stock settings (its still worth setting these manually) as you will have to mess with it again later (unless you have an unlocked multiplier).
There is no way to change the overclocking without chaning the BCLK, or by selecting the DRAM frequency corresponding to a memory multiplier.
There is no way to directly access the memory multiplier in the ASUS bios.
So it is by BCLK change or changing the DRAM frequency, but remember you will need to adjust the DRAM voltage
you can also change the memory by selecting the XMP setting, but that tends to bemore difficult for one: it will play with your existing OC settings, and two: if you OC with XMP on you will need to go back and change the DRAM frequency as you will most likely end up OC your RAM by a lot.