The Golden Smple varieties come pre-tested to overclock by a small margin... generally 5-10%.
Gainward will warranty the board if you run in at those pre-tested settings.
Should you choose to overclock beyond their pre-tested settings then your warranty is gone as usual.
Not a big deal really, because their pre-tested speeds are usually relatively conservative, enough so that even their non-GOlden Sample boards easily hit those speeds albeit unwarrantied.