The installation of ESXi 6.5 is pretty straightforward. It is recommended that you refer to the VMware Compatibility Guide web page to verify whether the server hardware is compatible with ESXi 6.5; this is available at http://www.vmware.com/resources/compatibility/search.php. Once you have made sure that the server hardware is compatible, the next step is to make sure that the server meets the hardware capacity requirements:
- The host should have at least two 64-bit x86 CPU cores
- AMD No Execute (NX) and Intel Execute Disable (XD) processor functions are to be enabled in the server BIOS
- To be able to run 64-bit operating systems on virtual machines, you will need to enable the use of hardware virtualization (Intel VT-x or AMD RVI) in the server BIOS
- A minimum of 4 GB of physical memory for hypervisor alone and an additional 4 GB to start hosting virtual machines
For more details on the hardware requirements, refer to the ESXi Hardware Requirements section of VMware vSphere 6.5 Installation and Configuration Guide (https://docs.vmware.com/en/VMware-vSphere/6.5/vsphere-esxi-vcenter-server-65-installation-setup-guide.pdf).