Code 12 error

[p3taoctane]

I have run more than two cards in my system before
I am getting this error message.

This device cannot find enough free resources that it can use. (Code 12)

If you want to use this device, you will need to disable one of the other devices on this system.

Here is my issue.

When I have two cards in my PC box I can boot up and displays (2 of them) both are live and working.
All good. I can even see the other two external cards I have in a cubix box)

When I put another card in the available internal slots (I have 4 more available) and hook them up to an internal (or even external power source so as not to put ANY power drain on the system) then boot up...

I here the system go through boot up and even give me the sing song tune ready for login. But I have no display on the screen.

I checked drivers all current (306.97) and octane can render on the 4 total no problem when the extra internal card is not powered on at boot up.

I have run windows upgrades and have had more than two of these same cards (580 Classifieds) running internally before...

I can't for the life of me think what might have changed... unless it was a windows update that happened while I had two cards installed for a period of time.

I would not even know to roll back to....

Anyone else had this issue?

Thanks for ANY ideas... 2 good cards dead not being used is a major crime in Octane land.