Hello,
did you ever find a resolution to this?
I am running the latest 6.5 release of ESXI and have an AMD 380 to which i was going to do pass through but I am experiencing the same problem of ESXi completely rebooting upon restarting or starting the VM with the attached AMD card in it,
As you noted other said drop back to 5.5, but his seems to be a problem with 6.5.
This thread is where i found similar issues:
This seem to be a larger issue, VMWare any input on this problem with pass-through with AMD devices in 6.5?