last night and today, a 12v power supply i have keeps running its fan. the only thing plugged into it is a usb hub and a device charger with nothing conencted to the device charger. the usb hub has an rtl-sdr connected to it, and a disconnected micro usb cable. the usb hub is connected to this laptop. i unplugged power from the usb hub, and the fan on the power supply stopped running. the rtl sdr is a little bit warm, but not as warm as i believe they get when running constantly at high rate.
oops: the usb hub is actually connected tyo a raspberry pi that is on with no keyboard plugged in, not this laptop. its attached lcd shows some usb errors regarding 1-1.3 and 1-1.1-port1 after the power cut.
this happened again after usb removal. it is likely a broken desktop that had powered itself on or something.