Claudio,
Please let me know which BIOS version do you have install on your system, since BIOS version 0096 fixed some issues related to memory, so you may want to try a BIOS update: https://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=22024&ProdId=3437&lang=eng&OSVersion=%0A%09%09%09%09%09%09%09%09%0A%09%09%09%09%09%09%09&DownloadType=BIOS
Regards.