CPU Fan error and overheating



Hi everyone, would really appreciate some help on what seems a serious problem that has developed:

My computer ran fine for ages. Now, on startup I had an American Megatrends screen, accompanied by a 'beep' and the message 'CPU fan error!' (next line) 'Press F1 to resume'.

I pressed F1 - did a bit of research on the internet to check it but the system seemed to work ok, so I logged on to play some games and didn't worry about it. I ignored it for a few weeks (stupid in hindsight, I know, but I wasn't paying much attention and didn't know if it was a serious problem) however today, whilst gaming, my PC just cuts out and immediately powers off. I am now seriously worried.

I turn everything off, leave it a bit, turn the PC back on and get the same American Megtrends screen with the same 'CPU fan error, press F1 to resume' message, plus a 'CPU temperature failure' message (can't remember the exact words, I can try and replicate if necesary.) So I guess something is really wrong with the CPU fan and the CPU has overheated?

I start doing some proper research on my laptop, then boot up my PC after an hour or two. I get the familiar CPU fan error message but no temperature message. I go into the BIOS settings and find the CPU temp and it just keeps on rising - all the way up to 70 degrees centigrade etc! Terrifying, as I know it's not supposed to go that high! CPU fan speed is 'N/A' and the Smart Q-fan Function is [Enabled].

Fan Auto Mode start speed temp is 25c and
Fan Auto Mode Full Speed Temp is 55c and even when just sitting there watching the BIOS the temp just climbs up slowly.

So I continue to boot my PC up and download Speedfan - shows the temperatures eventually stabilise at 90degrees (way too hot obviously) but the proper configuartion and use of speedfan looks WAAY over my level of competence.

Speedfan shows Fan 1: 0rpm
Fan2: 0rpm
Fan3: 0rpm
Fan 1: 0rpm
Fan 2: 1517rpm
lots of other fans all at 0rpm.

Belarc advisor shows I have:

ASUS Motherboard - M4A78LT-M Rev X.oX
Bus Clock 200 megahertz
BIOS: American Megatrends Inc. 0801 06/11/2010 (which is around when I bought the computer).
AMD Athlon II X2 250 - 3gigahertz
Windows 7
Nvidia GeForce GTS450 graphics

Please can you try and help me sort this out? I haven't modified the system I bought (from Overclockers - I have logged a ticket there and will on their forums when a moderator clears me to post) in any way. I'm not a PC expert (as you can probably tell!) But will happily follow clear instructions to help sort it out myself if it is not a defect with the component.

Thanks very much in advance for your help.
sounds like a cpu fan failure--if you are happy to open the side of your case you should be able to clearly see if the heatsink fan is spinning--if you dont want to open it then it should still be under warranty


Feb 8, 2009
Just pop the side cover off your case and look at the CPU fan. Turn on the computer. I'd bet money your fan isn't spinning or isn't spinning fast enough, and probably needs replacement.


Thanks guys, I was thinking it was a horrible technical problem but a simple clean out of the fan (which was horribly dusty) has solved the problem - fans are now working and CPU temp is back down to c.30 degrees. Brilliant, I am very relieved.

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