While installing ESXi 5.1.0 (making use of VMware native Image), you might observe ‘No network adapters were detected’ error message.
The reason for this is because the VMware native ESXi 5.1.0 image does not contain the required version(s) of network drivers for Network Daughter Cards (NDC) or Network adapters used in Dell 12G Servers.
You need to make use of the Dell Customized ESXi 5.1.0 Image posted at support.dell.com, which contains the required network drivers for all NDC’s and Network adapters used in Dell 12G Servers.
NOTE: Follow the steps listed in Downloading Dell Customized ESXi image for downloading Dell Customized Installer Image