Overclocking has always been iffy.
It starts out working and then parts age and now it does not work.
Unless you're running some very ram intense stuff I doubt you will see a difference.
memory specification for my motherboard is 2 x DIMM, Max. 8 GB, DDR3 1800(O.C.)/1600(O.C.)/1333/1066 ECC,Non-ECC,Un-buffered Memory. It was working fine at 1866mhz but unfortunately it has stopped working and it now only working with 1333MHZ. Can anyone suggest me what is the solution so that it could work with higher frequency as before