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 is installed, but the same problem happens in both BIOS and Windows: the system starts normally, then after roughly 20–40 seconds the screen goes black and the monitor reports no signal. The PC itself stays powered on, with the fans still running. I'm not sure whether the issue is related to the riser, power supply, cabling, or installation. What should I check first?
2 Answers
The SF1000 should generally provide enough power, but the RTX 5080 can produce brief transient spikes. Make sure the power supply and GPU cables are connected correctly and that the supply meets the required modern ATX standard. I’d also test the system without the riser cable if you can, or set the motherboard’s PCIe slot manually to Gen 4 instead of Auto. Some risers become unstable when the link negotiates automatically.
Since the problem occurs even in BIOS, it probably isn’t a Windows or driver issue. Start with the simple checks: reseat the RAM and GPU, confirm all power connectors are fully inserted, try another HDMI or DisplayPort cable, and test the display from another output if possible. Small-form-factor builds can be especially sensitive to components not being completely seated.
That’s possible—I’m going to take the build apart and carefully check the seating and connections before changing anything else.
I’m using a Corsair SF1000, so power capacity should be reasonable. I’ll try forcing the slot to PCIe Gen 4 and see whether the riser is the cause.