While using XMP profiles is technically a form of overclocking and Intel does not officially condone overclocking, using XMP profiles is not going to void your processor's warranty. That said, Intel does not warrant that your processor will work properly at any speeds above that validated by Intel.
Bottom line, while it isn't going to void your warranty, if it doesn't work, it's your problem (Intel's answer will be to get memory that runs at or below warranted speeds).
P.S. I would also comment that the quality of the motherboard has more to do with whether faster memory will work than does the processor.