while trying to achieve a 4GHz overclock, with a base clock of 200MHz and a multiplier of 20, if you decrease the memory multiplier down from a 2:10 to a 2:6 (to avoid cranking your memory up to 2000MHz), you are now under-clocking your memory (which for our sake is rated at 1333MHz) 733MHz.
Is this avoidable? Is this acceptable?
More aboutmemory underclocking
You can always try 8x and see if you can get it to run at 1600. If not it all depends on what cpu multiplier you have (don't know what processor) as to what ram frequency you can obtain.
processor is going to be a core i3-530. It will top out at 1333MHz