My desktop stopped powering on after several days of heavy rain. It is kept indoors, and this has happened once before without causing any obvious damage, but now the system will not turn on at all. I tried removing and reinstalling the RAM, clearing the CMOS, using different wall outlets, and checking the cables, but nothing changed. The motherboard may still be receiving some power because of the internal lighting, although the PC does not boot. I previously had an M.2-related issue where a technician said the motherboard had a short circuit, so I am wondering whether it has failed again or whether the power supply could have been damaged by a surge. What should I test before replacing the motherboard?
3 Answers
Before blaming the motherboard, rule out the case power button. Disconnect the front-panel power-switch connector from the motherboard and briefly bridge the two power-switch pins with a screwdriver. If the system starts, the case button or its cable is faulty. Also reseat the main 24-pin motherboard connector and the CPU power connector, but unplug the PC first and avoid forcing anything.
A previous short-circuit diagnosis does make the motherboard worth considering, but the PSU could have been damaged by the same event or could have caused the earlier problem. Do not open the PSU; its capacitors can retain dangerous voltage even after it is unplugged. If there is any smell of burning, visible moisture, corrosion, or scorching, stop testing and have the PSU and motherboard inspected or replaced.
Rain itself should not affect an indoor PC unless moisture got inside, but storms can cause power fluctuations or surges. The power supply is a strong suspect because it can fail while still allowing a few LEDs or RGB lights to turn on. If possible, test with a known-good PSU rather than relying only on the paperclip test, since that test only shows whether it starts up and does not confirm that it can deliver stable power under load.
That makes sense. I’ll try testing with another power supply before assuming the motherboard needs to be replaced.