I've assembled a new system with a GIGABYTE X870E AORUS ELITE X3D motherboard, Ryzen 7 9850X3D, 32 GB DDR5-6000 memory, an ASUS PRIME RTX 5080 OC, Samsung 9100 PRO 1 TB NVMe SSD, Corsair HX1000i PSU, and an Arctic Liquid Freezer III Pro 420 cooler. The graphics card is installed in the main PCIe x16 slot and connected with a native Corsair 12V-2x6 cable. The CPU power connectors and 24-pin motherboard cable are also connected.
When I connect a monitor to the RTX 5080 using either HDMI or DisplayPort, I get no signal and cannot see the BIOS or POST screen. The integrated graphics works, allowing me to install Windows, but Device Manager reports Code 43 for the RTX 5080. Installing the NVIDIA driver temporarily clears the error, but after reboot the problem returns and the driver appears to be gone. DDU and several clean driver installations made no difference.
The BIOS detects the card as PCIe x16 Gen4. I've updated the BIOS, forced the slot to Gen4, tried booting without the NVMe drive, tested multiple cables and monitors, and allowed several minutes for memory training. The motherboard's red VGA light is off while using integrated graphics but returns after restarting with the RTX installed. The card's fans spin, and the card has also been tested in another PCIe setup. Could the GPU be defective, or is there anything else I should check?
2 Answers
The most useful next step is isolating the hardware. Test the RTX 5080 in another complete computer, and test a known-good graphics card in this motherboard’s main PCIe slot. That will tell you whether the problem follows the GPU or stays with the motherboard, slot, power delivery, or platform.
Even with a native 12V-2x6 cable, check that the connector is fully inserted and seated straight with no visible gap. It may also be worth trying the adapter included with the graphics card, since an imperfect connection can cause a VGA light, missing video output, and driver Code 43. Make sure the cable is not sharply bent right next to the connector.
The GPU fans do spin, and I’m currently using a dedicated Corsair cable rather than the included adapter. I’ll still check the seating carefully and test the adapter if needed.
The card works in another PCIe setup, so I’m narrowing the issue down to this system or its compatibility with the card.