warfreak
Talk to the hand!!!
I think the lower RAM can be overclocked, but if you have been using this for a while and faced no issues I don't see why you should even bother.
But for those who intend to upgrade later on should keep this in mind.
That is one of the reasons why me and girishpaiv are planning to have the RAM upgrade from Dell as RAM with 11-11-11-28 latency is not available elsewhere.
Couldn't agree more. The best practice IMO is to purchase a module of same brand and make to ensure both modules are of same frequency and latency.