[Rattleshock]

Just wanted to close the loop on this thread in the event any other HP Z800 users run into this issue. I purchased another Accel card and after some head scratching, decided on the following as my first attempt:

Slot 1: Empty
Slot 2: Accel card (this is the slot the graphics was in before)
Slot 3: Accel card
Slot 4: Accel card
Slot 5: Accel Core card
Slot 6: empty
Slot 7: Nividia Quaddro FX 580 graphics card

I hooked it all back up, turned it on, ran Digitest which passed everything and then rebooted.
Opened up protools 10.3.10 HD and everything worked. I did a full mix to see if having the graphics card in a different slot would interfere with the PCI bus in a weird way. No issue at all. I then stress-tested the system arming 64 tracks of audio with enough plugins to max out the HD4 cards and let it go for a few hours. Again, no issues.

Thanks to all who responded to my question. Any other HP Z800 users on windows 7 SP1 could follow this and have 4 accelerator cards installed internally in the tower. Works a treat! I am so in love with the TDM system. I know it’s older, but for me it is a match made in heaven.

Cheers!