Dell's PowerEdge M520 and M620 Blade Servers are the very same devices that work with its PowerEdge M1000e Blade Enclosure, which can accept 16 blades. Model M520 supports two, four, six or eight E5-2400 series cores and as much as 368 GB of 1600MHz DDR3 memory in its 12 DIMM slots. The M620 encompasses E5-2600 series parts, which add 10- and 12-core options. It can be packed with as much as 768 GB of memory in its 24 SIMM slots. Dell blades also can accept one or two hot-swap SATA, SAS HDD or SSD drives and a variety of mezzanine cards for adding networking and storage interfaces. They're both certified for Microsoft Windows Server 2008 or 2012 x-64 with Hyper-V, as well as Novell and Red Hat Linux, Citrix XenServer and VMware vSphere ESXi.