Help Fan Black Out!!!

I have got a new cpu fan+heat sink, fitted it but when i turn on my pc it says there is no cpu fan!

Can anyone help?

Did you hook it up to the power supply or the motherboard?

edit:
Assuming that you did hook it up to the power supply and not the motherboard. You can try what was discussed in this thread

Does your heatsink fan have a 3 pin rpm wire that plugs into the motherboard? If so, you need to plug it in or the bios will get scared and shut the system down thinking that there is a fan malfunction. You could turn the option off in the bios if you want though, you just might need to hook up your original fan to the motherboard header to get into the bios. The bios option would be somthing like this "shutdown if no cpu fan" or somthing like that anyways.

I tplugs into the psu and the mobo and it is pluged into them both correctly

Is it spinning? Also, if your fan does not have rpm monitoring, your motherboard wont see it. My A7N8X Deluxe used to bother me about it so I just turned off the speach reporter.

Oks how many wires come out of your HSF?Did the bios say what its saying now before you changed the fan?You need a fan that has three wire coming off of the fans motor.If your currant fan on the HS has only 2 wires coming off of the motor thats the prob.
Put a 3 wire fan on the HS ,then plug it into your adapter.Hook the yellow lead to the mobo header and the molex to the PSU connecter. THE FANMAN

Try unplugging it and plugging it a few times. There might be some residue of conformal coating left on the pins that didn't come off during the cleaning process, during manufacturing. Unplugging and replugging the fan header a few time usually takes care of this (if this is in fact the problem). If that doesn't work, try plugging in a spare fan you know works to the header, and see if it gives you the same error. Failing that, check to see if you have the latest BIOS for your board.