Ok, this is a weird one.  I have 4 gaming VMs setup and worked great with 4x 960s- no issues in any games no matter how long we play or what is thrown at it.  Upgraded 2 of the GPUs to 2070s and everything appeared to be great- passed through all devices from those cards to my machines and gaming was great- but only for so long.  After gaming for a couple of hours, those 2 machines will go black screen, flipping on and off the monitor.  If I unplug the hdmi from one card at that point- the other