ASUS Z77 Sabertooth CPU fan not working correctly

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Galmteam

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May 31, 2012
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10,510
Just put a brand new build together and it booted on first try, but the CPU fan only works every 4 or 5 boots. Every other time the cpu fan just twitches and spins a quarter cycle over and over again. I have it plugged in to the CPU_FAN header and have tried the CPU_OPT and CHA_FAN3 header. The fan is the stock Intel CPU cooler for the 3570k.
 
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Well if your CPU isn't needing any cooling than your fan won't spin up. I wouldn't worry about it unless you put the system under load and then doesn't spin up. Now it's possible that the fan isn't working and you could test the fan by using a power adapter, like listed below:
http://www.newegg.com/Product/Product.aspx?Item=N82E16812189119]Link Depot POW-ADT-3P4 Power 4 pin adapter to 3 pin fan adapter
12-189-119-03.jpg
 
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Since when? The CPU fan kicks in the second the computer turns out and never, ever stops spinning.
 
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OK new development.

I have plugged it into the CHA_FAN3 header once again and now it boots and beeps 4 times and says "CPU fan error!" as soon as it does that, the cpu fan comes and and spins at around 2500rpm. I disabled the force BIOS at warning setting and it looks like I could boot. Is it safe to run it like this?
 
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That's a pretty bad idea. If your CPU fan doesn't work and you try to force it, then you'll end up destroying that CPU. Just spend an extra $30 and get a Hyper 212 if you can fit it. Or contact the manufacturer.
 
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I've tried that. I'm ordering an aftermarket heatsink fan in the morning. The way I see it has to be the fan or the mobo's built in fan controller causing this seeing as how I've ran a chassis fan off the CPU_FAN header and it ran beautifully, and my heat sink fan wont run on any of the mobo's fan headers.
 
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I had practically this same exact problem a few weeks ago. Asus Sabertooth Z77, i5-3570K, using the stock intel cooler. It worked fine for about a day and then the fan just wouldn't spin up. After that I kept getting CPU FAN errors every time I tried to boot up.

I never did find out what the problem was, but after installing an aftermarket fan and heatsink the problem went away. I noticed my new fan only has a 3 pin wire, while the intel one had 4 pins. I have no idea if this had something to do with it. The weird thing is that, like you when I plugged it into one of the other headers, the fan spins fine, but the motherboard doesn't acknowledge it's presence. That seems to imply the fan itself is fine and the motherboard is at fault... Anyway, I wish you luck with it. If your problem is the same as mine, a new heatsink + fan should fix it. I got myself a nice Noctua to replace it.

Well if your CPU isn't needing any cooling than your fan won't spin up. I wouldn't worry about it unless you put the system under load and then doesn't spin up.
Click to expand...

Yeah... I'm going to have to disagree with that one lunyone. Even at idle the CPU heats up, if you plan on running anything more complex than YouTube you are definitely going to need some cooling on it. Good air flow on the inside of the case can only go so far, you need to get the air moving onto the CPU heatsink. I wouldn't risk letting the computer boot up if the CPU fan isn't spinning.

EDIT: I did take his suggestion to test the stock Intel fan on it's own... it does seem to spin up. I really think it's some kind of issue with the motherboard. I just can't be bothered to pack it up and send it all the way back to the supplier... The computer is working now, and that whole process would probably take weeks.
 
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Alright...Do you guys think that if I cut the PWM wire on my intel CPU cooler that it would work? Since it would essentially become a 3 pin fan connector?
 
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I don't think so... I mean I don't really know but that seems to be a rather crude approach to fixing it. And if it is a motherboard issue, you'll just be scrapping a perfectly good stock fan.
 
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It was the fan. I bought an aftermarket HSF and it spins up perfectly. Its a 4 pin PWM fan as well.

Playing Dead Space 2 on my new kick-a** gaming computer THAT I BUILT! :na:

It's a great feeling. Thanks for the help guys.
 
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SOLVED: Update your Sabertooth Bios to the latest was 1206 when I got it, I updated to 1504 fan spun up like a champ!

1. GO TO: http://support.asus.com/Download.aspx?SLanguage=en&p=1&s=39&m=SABERTOOTH%20Z77&os=30&ft=12&f_name=T7246_SABERTOOTH_Z77_V2

2. Download bios to a flash stick (which has to have a less than 4GB capacity)

3. make sure you re-name the .CAP file as listed in download pdf for your board

4. Press delete to enter bios on boot-up

5. go to advanced

6. go to tool tab

7. select EZupdate flash option

8. UPDATE FROM USB!

= FAN WORK TIME! :bounce:
 
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I have the same problem. Upgraded the BIOS but has not made a difference.

It seems to me the problem is in the mobo. I plugged in the CPU fan to a Chassis fan plug and works as a champion. I also plugged in the chassis fun to the CPU fan plug and also works! I can't make sense of this behaviour. ??????

I keep getting the message "Warning CPU Fan 0 rpm". However, when I switch the fan connections, the problem disappears.

Is someone else experiencing the same nonsense situation?
 
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