My desktop suddenly displayed a green screen while I was browsing, so I shut it down. After that, it would not power back on at all—no LEDs, fans, or other signs of life. This happened about a year after I replaced the graphics card. I'm trying to determine whether the power supply or motherboard is the likely culprit because I can afford to replace only one of them. Is there a safe way to test which component failed? I eventually got the computer working again by fully discharging it and waiting another minute before powering it on. The experience also convinced me to use proper surge protection or a UPS instead of plugging the desktop directly into the wall.
4 Answers
A complete lack of power usually points first to the PSU or the power path, but a failed motherboard can cause the same symptom. Also check that the 24-pin motherboard connector and CPU power connector are firmly seated. For future protection, a UPS is generally more useful than a basic surge strip because it can also handle brief voltage drops and interruptions.
If the system is completely dead, I’d start with the power supply. A replacement PSU is usually cheaper and much easier to swap in for testing than a motherboard, and many retailers have reasonable return policies. Before buying anything, check the wall outlet, power cable, PSU switch, and motherboard power connectors.
You can test whether the PSU starts independently by disconnecting it from the PC, switching it off, unplugging it, and disconnecting all of its component cables. Then bridge the power-on pin with a ground pin using the included PSU tester or a properly placed paperclip, reconnect power, and switch it on. If the PSU fan or unit does nothing, the PSU may be dead. This only checks whether it starts, though—it does not prove that it can deliver stable power under load, so use caution and follow a reliable pinout guide.
I’m glad to know about that test. The machine eventually came back after I discharged it for longer and waited before trying again, but this is useful information for the future.
Try removing the graphics card and any nonessential hardware, then clear the CMOS and attempt a bare-minimum startup with only the motherboard, CPU, and required power connections. If it reaches a diagnostic screen or gives an error about missing memory or other hardware, add components back one at a time until the problem returns. If there are still no lights or signs of power, focus on the PSU, motherboard, front-panel switch, and main power cables.
That makes sense. I managed to get it running again, but I’ll definitely keep the PSU-first approach in mind if it happens again.