Looking through the Intel warranty pages, it seems that if you bought the system from someone, you need to ask them about the warrany.
There are probably multiple warranties, perhaps one for the system, maybe one for the motherboard, another for the chip.
If you bought the chip directly from Intel (a boxed processor) then the warranty is included with the chip.
I don't know the specifics of what violates a warranty.
In general, external damage to a chip seems to void the warranty but I don't know if using 1600 mhz Ram violates the warranty.
The main warranty page for Intel chips is http://www.intel.com/p/en_US/support/warranty
On this page (under "how do I get warranty service?") there is a 'live chat support' with people much more knowledgeable about warranties.
Intel also has a web 'warranty assistant' at:
The assistant seems to end up at phone support, see:
I hope this helps,