I ran into an issue yesterday where both the led and the pump on my Corsair H150 were still function after the computer was shut down. I even unplugged the PSU, but no the pump was still powered and the light blue led light was still on. I thought I was going crazy, I checked everything, bios, settings, motherboard, etc. etc. After an hour or so I noticed I had a Gopro Hero 7 plugged into with a usb and hdmi cable. As it turned out the Gopro was somehow feeding power to the motherboard and tricking the pump to remain powered up. I unplugged the camera and presto the pump powered down as it should have. So you may want to check if you have any similar accessories plugged in. I am still baffled as to the exact nature of this bug, I am just going to avoid leaving things like that plugged in.
