I recently built a small-form-factor PC with a Ryzen 7 9800X3D, an ASUS B850-I motherboard, and an ASUS Prime RTX 5080 connected through a PCIe 4.0 riser cable. Windows installed successfully, but the display repeatedly goes black after roughly 20–40 seconds. The monitor reports no signal even though the computer remains powered on and the fans keep running. This happens in both the BIOS and Windows, so it doesn't appear to be limited to an operating-system or driver issue. What should I check first?
3 Answers
The power supply is probably not the first thing I’d suspect if it’s a quality 1000-watt unit, but make sure the GPU power cable is fully inserted and that you’re using the proper cable supplied for the card. Since the problem also occurs in the BIOS, focus first on the riser, GPU connection, display cable, and PCIe settings rather than Windows drivers.
Because you’re using a riser, manually set the motherboard’s PCIe slot to Gen 4 in the BIOS instead of Auto. Some risers and newer boards have trouble negotiating the link automatically, and forcing the supported generation can stabilize the display signal.
Start with the simple possibilities: try another known-good HDMI or DisplayPort cable, verify the monitor is connected directly to the graphics card, and reseat the RAM, GPU, power connectors, and riser cable. A loose connection or faulty cable can cause exactly this kind of intermittent signal loss.
That’s definitely possible. I’m going back through the build and checking that everything is seated correctly.
I’m using a Corsair SF1000, so power should be adequate, but I’ll try forcing the slot to PCIe Gen 4 and see whether that changes anything.