Help Please!!!!!!

I bought one of those 4 LED case cooling fans off e-bay.It works fine until I shut down the system,were in the course of shutting down, the computer goes through its process of shutting down and the fan boots the computer back on,I know its the fan because when I unhook the fan the computer shuts down properly.Whats causing this to happen?I had to replace the old fan because the bearings went out of it,any help would be greatly appreciated......THANKS....Cody

Does fan attach to the motherboard fan lead?

Sounds like you are exceeding the limit of the motherboard lead or that lead is trying to sense fan speeds and the LEDs are screwing it somehow.

The motherboard fan lead has a limit on watts it can drive.

As for sensing fan speed, that is tied to the PCs hardware monitoring, and most newer PCs the hardware monitor ties to the ability to shut the system down (maybe your hardware monitoring is getting screwed and causing power up).

Other possiblity would be somehow that fan is bleeding power back into the motherboard and causing problem. Some boards if # milliamps active on the motherboard it will power itself on (where # is the amount of milliamps). Fans operate off a magnets and coil, and if you spin the fan the magnets will induce power into the coil (maybe fan inducing power while it is spinning down, and induced power bleeding back into board and causing it).

Next would be it is attached to the power supply and possibly screwing the 5 volt line. Maybe the LEDs running from 5 volt, if attaches to standard 4 wire drive power connector is their two wires into the fan or four wires? If 4 wires from power cable into the fan that means it is drawing from 12volt and 5 volt. The 5 volt ATX to the motherboard has to provide #amps for the ATX to work properly (where # is the number of amps, dependent on motherboard).

Another thing I could think of is the setting in the bios that if power cut to PC (AC power loss) the PC will automatically power up when AC power comes back. Quite possibly the fan screwing power supply and thinks AC power loss. You can disable the auto power on when power failure in the BIOS (if your system has this option). Disable if enabled and if it fixes that would mean fan is screwing the power supply or the power supply is at it's limit.

Does the fan attach to motherboard? How many amps/watts is the fan? What motherboard do you have? If the fan attaches to power like a disk, are their four wires to the fan or two? Do you know make and model of the fan?

Sorry it took so long to get back. First off I'm not real computer smart, that said I was able to use your advice to fix my problem,it took me a while to figure how to get into the BIOS of my system,not knowing what I was doing I figure there would be no harm in just setting everthing to default, and it worked, the computer works like its suppose to,and that makes me truly appreciative of your advice and knowledge that fixed my problem.....THANK YOU ......Cody