The virtual machine configuration tasks that you can perform when you connect directly to an ESXi host or vCenter Server system with the vSphere Client are limited.
The following virtual machine features are unavailable or read-only in the vSphere Client:
128 vCPUs for virtual machines with hardware versions earlier than version 10
32 Serial Ports for virtual machines with hardware versions earlier than version 10
255 PVSCI devices
SVGA for virtual machines with hardware versions 10 and 11
Smart card authentication
SATA controller and hardware settings
GPU 3D render and memory settings
Tuning latency settings
vSphere Flash Read Cache settings
vCPU reference counters
Ease and scheduled hardware upgrade
Default compatibility level
VMware Tools reporting and upgrade
Use the vSphere Web Client as the primary interface for managing the full range of virtual machine functions available in your vSphere 6.0 environment.