Question Loss of display output from a used RTX 3090 ?

[alpoke83]

I bought a 'for parts" RTX 3090 EVGA off CL. The previous owner claimed sudden power loss and then no display out after that, trying many things on his own. He said the card lit up and fans worked but couldn't figure it out.
I took it home and it booted up without issue with an x470 and a x570 board. I ran a few bench marks and played with reducing power limits to manage thermals with afterburner last night without issue.

Today I was working on reformating my second, game drive an Intel 660p but it looked like it went bad. I removed the drive, and when it tried rebooting the rtx would not display out. The rgb and fans worked but no display out.

Tried HDMI and dp cables on 2 monitors and nothing. Was able to add a GTX 745 to the second pci slot to get display out. Initially, device manager showed nothing for a few minutes then I heard a shift in the sound of the 3090. It showed in device manager and displayed when I moved the HDMI cable to it. It ran for several minutes and through multiple restarts.
When I removed the GTX 745 it stopped displaying out. It has happened in that partner two times. And I can't figure out why a hardware change is affecting the output of the 3090.

System
MSI x570 gaming plus (current bios)
2600x
2x8 3000hz in 2nd-4th slots from cpu,
Aio cooler
EVGA 650gold
EVGA ftw rtx 3090
Zotac 1060 6gb
Gtx745

Thoughts on why and things to try will be helpful.

 

[helpstar]

reset BIOS after changing hardware

 

[alpoke83]

I updated the bios on the motherboard after no display and ran a patch from Nvidia for the rtx 3090 .
All of the no display issues have been at start up. Not during use.

The 3090 is currently working but I have to leave the GTX 745 in the system. A few times it has not worked on start up, and I have to use the 745 for about 5-10 minutes then the system with recognize the 3090. Then I can swap the HDMI cable over.

 

[alpoke83]

It ran and booted multiple times last night and today so I removed the 745 and the ssd. Without touching anything else, and it booted fine again. I turned it off and then added anti sag bracket, and no display out. This may be a simple heavy card in pci slot issue. I'll try more.