A great read on RAM timings
In a way RAM can have it's own speed if you set it that way because the RAM's speed can not keep up with the CPU's speed.
That was refering to the CPU's HTT, so when the CPU is OCed the RAM is also OCed which brings several things into play.
1. The RAM's ability to run at the same speed as the CPU. If it cant you have several options and can use all of them ot acheive the highest stable speed.
a. Always test with Memtest ... use the Memtest method in the below link for quick testing ... links for other software to test for stability are there to... OCCT, Prime, etc...
b. Increase the RAMs vdimm or voltage.
c. Increase the RAM controler voltage
d. Set the RAM speed lower... 166/333 or 133/266 to use a divider to run the RAM at faster timings but slower speeds.
e. The RAM's HT multiplyer... it uses 5x default and is multiplyed by the HTT so @ default it's 5x200=1000
You want to keep the 1000 in mind because it can run between 800 and 1000 very well. Much past 1000 can cause instability so
an HTT of 201-250 set the RAMS HT to 4x
3x for 251-333
2. To determine how fas the RAM can run, the above will help and ...
If you set your CPU multiplyer to 7x the OCing will not be effected by the CPU nad will actually be OCing the RAM to find it's max stable speed.