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&v=5AOylHaCyUA#t=113s
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.
As far as 48GB (6x8GB) many X58's and i7-9XX can run 48GB; (while I'm on his site) see - http://www.youtube.com/watch?v=g0eGh3cPt0w