Customers upgrading to Citrix XenServer 7.0 on the Dell R720 and Dell R730 and a fresh install of XenServer 7.0 have reported that any VM with a virtual GPU assigned (regardless of which vGPU profile) to it would not power on. An error message of "an emulator required to run this vm failed to start" is seen. Un-assigning the virtual GPU from the VM, the VM would power on, and boot like normal. Systems had worked without issues with XenServer 6.5 using virtual GPUs
Upgrading the BIOS on the Dell Server to a newer version resolved the issue. E.g On the Dell PE R720 updating the BIOS to 2.5.4 from 2.5.2 resolved the issue and VMs were able to power on, and fully boot up. Dell are aware of this issue and customers are advised to contact Dell for BIOS updates.
Citrix XenServer 7.0
Dell R720 and R730 servers
NVIDIA GRID vGPU using GPUs including M60, M6, K1, K2, M10