While learning electronics by reverse-engineering board schematics, one of my computers started making an intermittent growling noise. I suspect a failing fan bearing. Probably not a big deal, as mechanical things wear, and failure is inevitable. I traced the sound to a Channel Well Technology GPS650S power supply's internal fan. This computer has a 9th gen Core i7 CPU, which launched in 2019 so this power supply has been running for roughly four years. This is on the short end of PC cooling fan lifespan, but hopefully just bad luck of being on the short end of the bell curve.

Looking on the bright side, I know how to replace a failing fan. So given a choice I prefer this failure mode versus blowing a non-user replaceable fuse or burning up.

Getting past a few "no user serviceable parts inside" and "warranty void if removed" stickers opened up the enclosure to access the 120mm 12VDC fan.

Something's definitely wrong with the fan, as the label isn't supposed to get puffy and shiny in the middle like that. This is consistent with friction heat generated by a failing bearing.

Fortunately, the fan seems to be plugged in to the power supply control board with a commodity JST-XH 2-position connector.

Sitting on my shelf are multiple 120mm 12VDC cooling fans that can serve as suitable replacement. One of them even has a JST-XH connector already installed. Judging by the sheet of airflow control plastic on this fan, it was salvaged from another power supply. Probably the the one that blew an inaccessible fuse.

Unfortunately it was not that easy, but that was my own fault. I connected it up to my bench power supply dialed up to 12V DC for a test. It spun up nicely and when I reached over to disconnect power I knocked the fan grill into the fan. The fan, spinning at full speed, dealt with the sudden stop by snapping off a blade. Rendering the fan useless. D'oh!

But I had other fans to spare, including one with an Antec sticker that probably meant it came from the power supply that went up in smoke. It should work just as well, merely a bit less convenient for me because I had to cut off its existing connector and crimp my own JST-XH compatible connector. This time I was more careful with the spin-up test and did not break a blade.

The power supply is now back in action, running quietly with a replacement salvaged fan. And now I have two broken fans on hand: one with a bad bearing and another with a broken blade.