Quite recently I’ve deployed a POC setup for a customer who wanted to leverage NVIDIA vGPU for their XenDesktop environment. In regards to all the prerequisites being met the VM’s wouldn’t boot when trying to test this on the base build of vSphere 6(the latest version that could be downloaded from the site) and the dedicated hardware.
After some time troubleshooting the issue was in the base build of VMware which was downloaded from the site. It included a hotfix which in turn would kill the vGPU support / integration. The resolution was updating the host to the latest level of patches. (the host at first was standalone being prepped to be inserted into the cluster of the customer, once joined update manager could do the rest)
For reference see the following articles:
https://kb.vmware.com/s/article/2150498
https://kb.vmware.com/s/article/2143832
Hope this helps!