MP 1,1-5,1 Mac Pro 5,1 PCIE Slot 1 Not Working

[Abraxen]

Hi Everyone,

I recently picked up a cheap classic Mac Pro 5,1 single CPU system. Had a non-compatible GPU installed in slot 1. I installed a 5770 in slot 1 and do not get video. Installed in slot 2 and the video works fine. I will say that the locking mechanism for the PCIE slots isn't necessarily that functional.

I've been searching quite a bit on this and there are very few hits on this situation. Wondering if anyone had any thoughts on this. Perhaps the prior owners damaged the slot? Anything I can try to get it working again?

 

[flat4]

find another pci card that works and stick it in. If you boot see if the systems sees it, if not you got a dead slot

 

[joevt]

Does the 5,1 have any other PCIe cards in any slots? Try removing them before trying slot 1 again.

 

[Abraxen]

Update with weird behavior.

What I recall happening the first time I started this machine up with the 5770 in PCIE1 was the fan ran at full speed and nothing else would happen. Move to slot 2 and it would bong and function normally.

I had installed High Sierra with GPU in slot 2. After I made the original post I decided on a whim to try slot 1 again, and it worked fine.

Fast forward to today when I removed the tray and upgraded the CPU. Turned on system and GPU (in slot 1 now) had same behavior with fan at 100% and no boot/bong. I thought I goofed up CPU swap, so switched back and same thing. Remembered the GPU issue, switched to slot 2, and booted up. Swapped CPU again and booted up.

After I got into High Sierra, I shut down system and swapped GPU to slot 1 and it booted up fine again.

So is there something weird going on that's maybe related to the tray? I don't recall if I took the tray out when I bought it, but I also have no idea what the prior owner did. I can unplug the system and it will still boot up in PCIE1, so doesn't seem power related.

 

[Abraxen]

Does the 5,1 have any other PCIe cards in any slots? Try removing them before trying slot 1 again.

To answer your question, no the behavior was only with GPU installed. If you read my last updated I was actually able to add a PCIE to NVME card after I got slot 1 working. When I removed the tray though, it would have the same issue with or without the NVME card.

 

[tsialex]

There are dozens of reports in the Mac Pro forum of one of the PCIe 16x slots damaged/not working. The damage was caused by GPUs that require more than 75W from the PCIe slot, like the reference model AMD RX 480, some Dell made RX480/RX 580 and some NVIDIA TITAN GPUs. The over current overtime damage the SMD fuses, can burn PCB traces and even physically damage the slot contacts.

Some backplanes that seem to be perfectly with visual inspection can be like yours, just partially working - like working just with a NVMe blade (require only x4 and very low power draw), while others more damaged have all the SMD protection fuses open.