Hello, I'm running Citrix-XEN on two R550 Workstations. Each with 4 Pieces of 2GB RAM. BIOS is al 1.6.xx Version. Because 8GB is not very much I tried to upgrade to 4 * 4GB, but without success. Thats what the Manual say's about Memory. - Registered ECC FBD DDR-2 667/533 - Automatic memory bus frequ...