The PSU tester fails to illuminate, but the computer functions normally.
The PSU tester fails to illuminate, but the computer functions normally.
I acquired a standard PSU tester that matches the one you described. I used it to verify the PSU for my GPU, which failed. The tester fails to light up when connected via the 24-pin cable, except for ATX 12V 2x2 and 2x4 connections, which are not reachable without disassembling the CPU cooler. No display appears, and the fans do not start. After checking all switches and connections, I tried it with a different PC/PSU, and the tester works normally from the 24-pin port but only reports issues when no other 12V cables are connected. The PC functions correctly without the GPU. It seems another common protection might be missing—such as pin shorting on secondary ATX cables in some PSUs. I’m wondering if I can test it differently, perhaps using a multimeter on a live PC, though that could be risky.
The CPU 12Vs operate on a separate rail compared to the 24-pin connector.