you'll be lucky if you get it replaced. usually over clocking voids any warranty on your cpu.
running overclocking with a stock cooler is a terrible idea, i hope you had an after market cooler to compliment your I5.
you might wonder how they would know you over clocked? they will look at the transistors and will be able to tell.
And as a personal preference, msi sucks. I would go with ASUS as their mobos are epic and customer service/support is legendary.
I wasn't running a stock cooler. Had a Corsair H100i liquid cooler. Well it doesn't hurt to try and RMA it. Worse comes to worse they just send it back.