My PC suddenly stopped responding after I put it to sleep. When I came back, pressing the power button did absolutely nothing—no fans, lights, or other signs of life. The Corsair SF750 passed the manufacturer's paperclip test, so I'm unsure whether the PSU is actually the problem. I don't have spare components for testing, and this was my first build about three years ago. I'm not convinced it's the case power-button cable since the system was already running before it went to sleep. The build uses a Ryzen 5 7500F, an ASRock Lightning B850I motherboard, a Corsair SF750, and a Lian Li A4-H2O case, with 32GB of TeamGroup memory.
3 Answers
Try briefly shorting the two motherboard power-switch pins with a screwdriver. That bypasses the case button and cable, so it’s a quick way to rule them out. Also make sure the 24-pin, CPU power, and PSU modular connections are firmly seated. The paperclip test only shows that the PSU can start up; it doesn’t prove that it works correctly under load or with the motherboard connected.
A sleep-state or BIOS/firmware issue is possible, especially if the computer became unresponsive immediately after sleeping. Clear the CMOS, disconnect power for a few minutes, and then try a fresh boot. If it happens again, update the motherboard firmware and consider disabling sleep temporarily. If there are still no lights or fans after that, test with the minimum hardware and suspect the motherboard or PSU rather than the operating system.
Since reseating the RAM brought the system back and restored display output, the memory may simply have had a poor connection. Shut the system down fully, unplug it, and reseat the modules carefully. You can also try booting with one stick at a time if the problem returns. Replacing the motherboard immediately may be premature, although recurring sleep or startup issues could point to firmware or board problems.
I reseated the RAM and it started working again, including video output. I’ll keep an eye on it before replacing the motherboard, since it has caused me trouble before.