I'v been in this for 22 years and if you call intel they say running the Processor out of listed specification voids the standard warranty. intel Phone Number: 1-916-377-7000
The motherboard manufactures don't care if you overclock the only thing you can damage is the intel CPU or BIOS and the board has to be sent in.
A long time ago we use to get new motherboards when we would RMA for the first year, that was great. There were so many RMAs that board manufactures made a RMA departments. Most boards go in with no problems and are sent back to the customer in the same condition. From what I see over the years if you have a real problem that will show up in default settings they will fix or replace and not tell what they have done, even if they did not fix the problem they say it is fixed, I see that all the time.
In the RMA department they don't test overclocking of any kind even memory, they just look for default settings problems. Gigabyte Phone 1-626-854-9338