MP 1,1-5,1 MP4,1 Graphic cards work only in slot 3 except GT120 (in any)

[PlatypusRex]

Hello everyone,
I have some weird issue with graphic cards and am out of ideas. Hopefully one of you knows what’s going on with my Mac.

I got the Mac Pro second hand, so I don’t know anything about its past. It’s a MP4,1 which got the upgrade to the 5,1 firmware.

The original GT120 works in any slot just fine. However, every other card I try to install won’t work unless I install them in slot 3.

If I install them in slot 1 there is a beep, but no picture.

If I install them in 2 or 4, there is no beep, no picture.

If I install them in 1, 2, or 4 and also install the GT120, the system information doesn’t list them even as a PCI device nor does lspci list them.

Cards I have tried:
Quadro 4000 Mac Version
GeForce 560
Some ATI Radeon
about a dozen other Geforce cards

What’s special about the GT120 that it works in any of my board’s slots?
What is special about Slot 3 that all cards I tried work in this slot, but then this slot only (except the GT120)?

Will there be a significant difference to run cards in slot 3 instead of 1 or 2? Because of the x16/x4 thing? I would like to play occasionally some games (10 years old or older).

Thanks in advance!

 

[KeesMacPro]

IF:
- the cards are known to work
- you connected them with (known to work) mini 6-pin cables on the LogicBoard (if there is/are powerconnector(s) on the card)
- the card is compatible with the OS installed

then it sounds to me like a damaged LogicBoard.

For checking the compatibility of the GPUs you've tested:

GPU Compatibility List for cMP

Content: 1. Summary 2. Information on common GPUs that can be used in cMP 3. GPU power consumption 4. Color compatibility 5. Flashing nuances 6. What to choose? 7. Useful links. 1. Summary 1.1. There are 50+ GPU types that are compatible with cMP (classic MacPro = Mac Pro 1.1-5.1/...

forums.macrumors.com

 

[PlatypusRex]

Since all cards work in slot 3, I am very sure, that it’s neither a problem with the connection, the 6-pin cable, nor the OS and its drivers. So yeah, it must be an issue with the logic board.

What confuses me is that the GT120 works in slots 1, 2 and 4 without a problem, so I would guess those slots should be okay as well?

So I still don’t understand the underlying problem, but if I would I would hope there might be an easier/ cheaper solution than a board replacement.

 

[Macschrauber]

Try deep cleaning your nvram.

Keep holding Cmd-alt-p-r during cold boot until the mac chimes 4 times

 

[joevt]

Do you have any other cards installed? Try with only each GPU.

 

[PlatypusRex]

Do you have any other cards installed? Try with only each GPU.

only difference (depending if the cards are tried without others, or together with the GT120) is the “problematic” cards being in slot 1: single there is no beep and no boot, in combination the GT120 works as expected, but the problematic cards are not recognised at all (except if they are in slot 3 as described in my first post).

 

[PlatypusRex]

Tiny update: An evga GTX650Ti works also in slot 1. I have no clue, what's the criteria whether a card works or not in my mp's slot 1.