Usually fan holding screws have seal over them, so it probably will void warranty. Vendors might overclock cards a bit too high, which causing temperature issues. Also, nothing wrong with under-clocking and under-volting card a bit. You lose a bit of performance for a major temperatures and voltage draws. You might even improve performance by undervolting card, since you won't be hitting temp threshold, which cause massive clock drops. If limiting frames doesn't fix temperature issues, consider downclocking a bit.