1866 MHz or 2133 Mhz modules?

[satmanino]

Hello all,

I'm the owner of a Mini-ITX system based on Zotac Z68-ITX and I've a doubt on choosing the best DDR3 module.
I read several post and my choose is now on one of these two kits (both RipJawsX available on my country (Italy)):

F3-14900CL8D-8GBXM 1866 MHz 8-9-9-24-2N
F3-17000CL9D-8GBXM 2133 MHz 9-11-10-28-2N

My PC runs on I5-2500K and I'd like to do a little overclock (about 4 GHz).
Which memory module performs better? Is it better to choose a 1866 MHz with faster CAS latency or 2133 MHz with slower latencies?
Overclocking 1866 MHz to 2133 MHz will get the same results to have a 2133 MHz modules?

Thanks in advance for your support!!

[Tradesman]

CPU and mobo both support 2133, so I'd head that direction. You'd prob be able to OC the 1866 set to 2133 at CAS 9, then on the other hand the 2133 set will OC higher yet.

[satmanino]

Thank you for your answer.

What happens if I leave my system untouched (not overclocked)? Which memory module will give the best performance with default memory and CPU clock?

Thanks again.

[Tradesman]

Not positive it will run 2133 w/o an OC, easiest is to have latest BIOS, enable XMP and select profile, it will adjust system to run at DRAMs rated spec (if BIOS is up to snuff)