Glad to have found this thread -- I hadn't looked here, as it's in the ESXi 4.x section.
I used the information to create a Home Server from Don's blog: http://thehomeserverblog.com/esxi/esxi-5-0-amd-whitebox-server-for-500-with-passthrough-iommu-build-2/
It all worked fine for 18 months passing through an ATI Radeon HD 6450 to Windows 7.
I recently upgraded from ESXi 5.5 to 6.0, and it continued to work for two weeks.
Last week, after applying Windows Updates, my Windows 7 VM user interface began to lock-up. The VM would boot OK, but output via the passed-through graphics card and input passed-through USB card (for keyboard and mouse) would freeze. I had some external network WMI monitors running, and it was obvious the VM was still running.
I tried a few things, including building up a whole new VM with Windows 7. It fails in exactly the same way. If I remove the passed through video card and USB bus, it works fine.
I do not currently have any manual configuration items set (pciHole, etc.). The 3 GB of RAM I have allocated to the VM is reserved in the GUI.
Any suggestions? Are there some manual configuration tweaks I should try? I did also create a post in the ESXi 6.0 section but no replies over there, and it seems all the passthrough action is in this thread.
Thanks
John