- always update your BIOS (sometimes contains new memory profiles and other things)
- always run MEMTEST at least once and always after changing any settings related to CPU or RAM
- if you OVERCLOCK the CPU, you may need to drop the RAM MULTIPLIER so that the RAM frequency does not exceed its maximum
For other's 'reference' a couple of possibilities, first accessing >16GB requires Window 7 Professional, Ultimate or Enterprise. Next some X58 have Memory Configuration Protect; see http://www.youtube.com/watch?feature=player_detailpage&... or its equivalent. Lastly, fiddling with the BIOS and manually setting the RAM can indeed help or Clear CMOS, and if needed using the latest BIOS.