On Dell PE R720 with two NVIDIA GRID K1 cards and a fresh install of XenServer 7.0 Any VM with a virtual GPU assigned (doesn’t matter which vgpu profile) to it would not power on. Would get an error message of “an emulator required to run this vm failed to start”. If I unassign a virtual GPU from the VM, the VM would power on, and boot like normal. Everything worked fine with XenServer 6.5 using virtual GPUs
To fix this, I updated the Dell PE R720 BIOS to 2.5.4 from 2.5.2. VMs now power on, and fully boot up.
Hope this helps anyone else with this issue.