I recently got a used PC from a friend and reset it, but it now powers off unexpectedly, usually soon after starting up. It can happen while the computer is idle, opening browser tabs, or browsing files, so it does not seem limited to gaming or other demanding tasks. The PC turns back on immediately afterward. I am trying to troubleshoot it myself and avoid paying for professional repair. The known hardware is an Intel Core i7-9700 and an RTX 2080 Super. I am using an older power cable because I did not have one available, although it has no visible damage. Could the cable or power supply be failing, or should I look at overheating, loose connections, or software problems?
1 Answer
Start with the simple hardware checks. Turn the PC off, unplug it, and reseat the 24-pin motherboard cable, CPU power cable, GPU power cables, RAM, and graphics card. If the power supply is modular, check the connections on the PSU side too. Also inspect the case for heavy dust, make sure every fan spins, and monitor CPU and GPU temperatures with a hardware-monitoring utility. Temperatures near 100°C could trigger a protective shutdown. Since the PC powers right back on, a failing or unstable PSU is also a strong possibility, especially if it is old or underpowered for an i7-9700 and RTX 2080 Super. If possible, test with a known-good, appropriately rated PSU and a properly seated power cable. A full clean OS installation and updated chipset/GPU drivers can rule out software issues, but sudden loss of power usually points more toward power, heat, or a loose connection than ordinary file corruption.
It turns back on immediately and seems able to run tasks while it is on. I will check the temperatures and reseat the cables first. I do not know the PSU model yet, but the power cable is older and came from another device.