The issue is the SATA III drives;  these weren't supported till Dell's 10th  Generation of servers.  They will show up as unknown devices, whether or not the bios is updated. Regards,
Hi, I have a PowerEdge SC1435 and have just tried to replace 2 * 500Gb WD drives with 2 * 1Tb WD drives and I am getting 'Unknown Device' for both SATA Port A & SATA Port B. SATA III drives & BIOS v2.2.3 Am I missing something here? Can this server support these drives? Does the BIOS need to be updated? Thanks in advance, Mark   
Poweredge SC1435 - HDD size limits?