I just installed a new RTX 5080 in my PC, but the monitor shows "No display detected" over both HDMI and DisplayPort. The GPU's lights turn on and the rest of the system appears to power up, but the motherboard's red VGA debug light stays lit. I tried setting the PCIe x16 slot to Gen 4 in BIOS, but it made no difference. If I remove the graphics card and connect the monitor to the motherboard's HDMI output, the system works normally. My power supply is an 850W 80 Plus Gold fully modular unit, and the motherboard is a Gigabyte B650 Gaming X AX V2. What should I check to get the graphics card working?
1 Answer
First confirm exactly what the motherboard’s red indicator means—on this board, the VGA light usually means the graphics card isn’t being detected or initialized. Reseat the card firmly in the top PCIe x16 slot, check that the slot’s retention clip is locked, and reconnect every required GPU power connector. Also make sure the monitor cable is plugged into the graphics card rather than the motherboard. If possible, test the card in another system or test another known-good GPU in this PC to separate a card problem from a motherboard or power issue.
The fact that the motherboard video output works with the card removed supports the VGA-detection diagnosis. I’d also clear CMOS after changing the PCIe settings, then try booting with default BIOS settings before changing the link speed again.