My PC was shut down and the power supply switch was set to O, but the power cable was still connected to the wall. When I reached behind the case to switch the PSU on, I touched the metal ventilation area and felt a small electric shock. The motherboard lights came on at the same time. The computer then booted normally into BIOS and Windows, with no smoke, burning smell, unusual noise, or visible spark. I shut it down, switched the PSU off again, and unplugged it. The PSU is a 750 W be quiet! model. Could this be caused by a grounding or electrical leakage problem, and is it safe to keep using?
2 Answers
The PSU brand and wattage alone do not determine whether this is safe. A PC can still show standby lights while the power switch is off, but a noticeable shock suggests a grounding fault, leakage, damaged cable, or another electrical problem. Don’t touch the metal part while it’s plugged in, and don’t rely on a surge protector as a substitute for a properly grounded outlet. Have the outlet tested and replace the PSU if the outlet and cable are confirmed good.
A small tingle from the case or PSU casing is not something to ignore. The motherboard LEDs coming on when the cable is connected can be normal because the PSU still provides standby power, even with its switch set to O. However, you should not be getting shocked. Stop using the computer until you check the wall outlet’s ground and the power cable, ideally with a receptacle tester or by having an electrician inspect it. If the outlet checks out, replace or professionally test the PSU rather than continuing to use it.
I usually switch it off when I go to sleep or when the computer is shut down, but I’ll leave it unplugged until the outlet and PSU are checked.
A surge protector may help with surges, but it won’t fix missing or faulty grounding. The outlet’s earth connection needs to be verified separately.