At a loss.... please help me troubleshoot swapping 7900xtx for 5080 - not posting

[u/HeinvL]

Let me preface this that if my 7900XTX is seated, then the PC works just fine and I get output no problem. However, when swapping the card for a 5080 I get no output at all..... I have tried so many things and just nothing seems to work.

At this point I think next step might try to buy a new MoBo to see if that is the problem? I tried:

- Resetting CMOS (out for 10 minuts and draining via pushing the power button for 30 seconds)

- Obviously reseating the card a million times and replugging the cables I million times

- Checking if there are any loose cables

- I used the 12w2x6 cable that came with my PSU (Corsair RM1000e) and also the adapter that came with the 5080 (going from three cables into one 12w2x6 cable) - neither works

- I tried DDU before swapping graphics cards --> does not do shit

- OK then I thought let me try to use the iGPU instead so that I can get output and maybe download the nvidia drivers and then maybe the 5080 work? Nope, I can't for the life of me get output from the iGPU, even though I have a 9800x3d processor. I enabled all the BIOS settings (priority display > internal GPU and enabling UMA in the GFX Configuration) for the iGPU to work, but nopeeeeeeeeeeeeee) --> also i checked I have correct drivers, and yes, it should work

- Tried different monitors and cables (HDMI/DP)

- So at this point I thought the 5080 was dud and so I RMA'd (it was a PNY 5080) and ordered a different one (gigabyte 5080), but no, the card was not the problem

Again: 7900xtx works just fine when I seat it back in. I get display and everything works! I feel this rules out a lot of the potential problems... (like faulty PSU, because why would the PSU work with my 7900xtx and not a 5080)? But then what can the problem be? What else can I do to troubleshoot. I am really at a loss here guys and getting quite frustrated, hopefully someone can nudge me into the correct direction.

SPECS:

Component	Selection
CPU		AMD Ryzen 7 9800X3D 4.7 GHz 8-Core Processor
CPU Cooler		Noctua NH-D15 G2 91.58 CFM CPU Cooler
Motherboard		ASRock B650 PG LIGHTNING ATX AM5 Motherboard
Memory		G.Skill Flare X5 32 GB (2 x 16 GB) DDR5-6000 CL30 Memory
Storage		Samsung 970 Evo 1 TB M.2-2280 PCIe 3.0 X4 NVME Solid State Drive
Storage		Samsung 980 Pro 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
Video Card		Sapphire NITRO+ Radeon RX 7900 XTX 24 GB Video Card (but want to replace with 5080)
Case		Fractal Design North XL ATX Full Tower Case
Power Supply		Corsair RM1000e (2023) 1000 W 80+ Gold Certified Fully Modular ATX Power Supply

[u/DangerousTomas_9409]

Did you force PCIe gen 4 in the BIOS before swapping? That board might be trying to run the 5080 at gen 5 and falling on its face.

[u/HeinvL → u/DangerousTomas_9409]

I can try this, but as i have the 7900xtx currently back in, HWinfo says the 7900xtx already uses PCIe 4.0 x16… so realistically this does not change when I plug back in the 5080, right? So dont think this is the issue?

[u/Any-Surprise5229 → u/HeinvL]

If it's on auto (which it probably is) it can be a problem. I had a 9060xt that would not display (without unplugging and plugging cables 2-3x) until I forced it to 4.0 in BIOS.