Nope. If you go too high you'll know it and it will reboot at default settings so you shouldn't ever have to manually clear CMOS. fyi, don't set memory timings tighter than 2-3-2-6 no matter what you have or even at higher CAS the other timings can't go lower than I've indicated. Other than that you should be fine. If it ever won't reboot after giving it a moment just power switch off then on, turn the pc on and pull the power cord as it starts to boot up. That'll reset the CMOS automatically every time.