Some cards use PCI-E slots only in Gen 4x1 mode and fail to boot on other systems.
Some cards use PCI-E slots only in Gen 4x1 mode and fail to boot on other systems.
The issue began after purchasing a 7900xt. No display appeared, so I replaced the motherboard assuming the slot was faulty. I removed my working 3070ti to install an AMD card, but neither worked in that slot. Once the new board arrived, the same problem persisted with the AMD. The 3070ti boots in that slot but only provides a 4x1 configuration, even under load without extra lanes. Its performance dropped significantly—almost halved. I’m seeking advice on why this slot fails for some cards and works for others. It seems the card is compatible in the next lower slot, which uses a different chipset but still offers only 4x4 lanes. My current specs are an I7 12700k Z690, Steel Legend 850, Corsair Multi-GPU, 32GB TRIDENT Z 3200MHz. I’m considering the CPU’s PCIe controller might be faulty as a possible cause. I’ve tried fresh OS installs, new power supplies, upgraded motherboards, and changed RAM, but nothing helped.
Because the motherboard is already swapped out, the CPU is probably the main issue. It could have bent pins or not making good contact with the socket, or it might just be faulty.
Are you utilizing the graphics slot holder? (You should.) Considering it's a Gen 5 PCI-E slot, have you experimented with changing the link speed and checking for improvements? Are there any other PCIe devices connected to the motherboard that might be causing problems? You could try removing wifi cards just to eliminate unusual issues. It seems like you placed it in the correct PCIe2 slot, especially since you mentioned moving it down to a 4x4 slot—it's a new socket, so compatibility issues could be present. These performance concerns seem quite significant, and I'm interested in learning how they were resolved.
Unfortunately I've already attempted to force gen 4 on the slot. All SSDs and M.2 Wi-Fi cards have been removed. Also, Amd isn't willing to provide a warranty unless I obtain diagnostic files from my PC with the card installed in the main slot, which undermines the warranty since it won't function there.
Great troubleshooting! Eliminates a lot of issues. Are you using the graphics slot holder for the GPU? (I noticed you didn't answer, so I'm assuming that's a yes). I tend to agree that it would have to be a CPU issue based on your symptoms OR the cards aren't making full contact with the motherboard causing them to negotiate slow PCIE speeds (3070 Ti) or not work at all (7900XT). Have you considered using the 3070 Ti to get some diagnostic data and try to RMA the CPU instead of trying to get AMD to RMA the 7900XT GPU?
I've owned this CPU since January and probably won’t get any support. I also sold my 3070ti to a friend who’s running it perfectly at 16x. I’m planning to spend that money plus some extra cash on a new graphics card instead of downgrading from the 12700k or switching to DDR5. Any ideas?
Ensuring stable power during the bios update significantly reduces the risk of bricking. The 13th generation offers solid gaming performance with consistent frame rates. It’s a strong choice, especially since no major performance improvements exist beyond that point. For those who prefer not to update, the 13th generation remains viable without costly upgrades. If you opt for a new motherboard, z790 models are fully compatible out of the box and remain supported on DDR4.