Yeah, clearing the CMOS would be the first thing to try. Then make sure the second ram stick is fully seated. The third thing to try would be to remove both sticks of ram and swap their positions along with clearing the CMOS. Remember when clearing the CMOS to also make sure you pull the power plug before hand.
If all that fails, then boot the PC with one stick of ram, go into the BIOS and raise the voltage for the memory by 0.05V or 0.1V and try again.