MP 1,1-5,1 Mac Pro 5,1 two 5770 graphics cards not working

[Shanebrujo]

I have a 2012 5,1 running 10.9.5 (this is a stable OS for my stable version of Pro Tools). Mine came stock w a 5770 and in order to run three monitors, I opted to get a second (used) 5770. The monitors I have are DisplayPort and HDMI only so the active mini display to dual link DVI adaptors weren’t an option for me. Anyway, after installing the new used video card in the slot above the current one, upon boot up the fan was full speed and only the ‘new’ graphics card was being recognized. I would like to run three monitors at the same time in PT. I’m not gaming or editing video so I don’t need some crazy video card. Any help solving this prob w the two 5770s I have would be ideal. If not, I could get a diff used card that would allow me to run three hdmi or displayport (full size) monitors. Thanks in advance

 

[reukiodo]

Throw in a cheap GT120 for just an extra screen without any tasking graphics.

 

[zedex]

Seems like they may not be sitting in their PCIe slots correctly. Make sure they are flush. Try putting one of them in Slot 3 (just for testing purposes). Then check you System Information > PCI and verify the link width is connected at the negotiated maximum (x16 for Slot 1, x16 for Slot 2 and x4 for Slot 3).

If you can't see BOTH cards in the system report - then one card is not working electrically - check the 6-pin to 6-pin auxilliary power connectors.

 

[MarkC426]

This was a bto option from Apple, and so it should work.
I had 2 5770 for years with 2 displays and a rift (so 3 really), worked perfectly.