Probably voltage related key is QPI/DRAM (Cpu VTT) and VDIMM memory volt balance. Read
http://i4memory.com/ramdetect and
Intel Core i7 920 Overclocking Introduction Guide on X58 as AUTO values isn't optimal.
In sticky threads at
http://i4memory.com/f54/ find an approximately bios template format and use that format to fill in your own settings you have tried and post it here so we can see what you have tried