CPU Fan Won't Spin Correctly

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Vigdisar

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May 10, 2012
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Hello,

I've just finished building my computer, and I've got a couple of problems. The first, and most troubling, is that my CPU Fan only spins on about 10% of boots (Comp Specs at end of post).

I've tried switching between the CPU_FAN, CPU_OPT, and two Chassis fan four-pin connections, and it didn't seem to be correlated to a specific four-pin. When I boot the computer, the fan will complete approximately one quarter-rotation every two seconds or so, stopping in between. Occasionally, however, (the 10%) the fan will start spinning ~four seconds after power on at what I presume to be a normal rpm and continues to run perfectly fine throughout the course of the session.

Booting when the fan does not spin results in a one-long four-short POST error (hardware fault according to ASUS manual) and causes the BIOS to throw a CPU Fan Error.

I don't want to have to RMA the whole CPU (just got it in the computer and would prefer not to have to wait for a potentially lengthy process). I'm trying to discern if it's a PSU issue, a CPU Fan issue, or perhaps a motherboard issue.

Checks performed:
- Multiple four-pin connections (no variance detected)
- Made sure cables were clear of fan

Computer Specs:
- Motherboard: ASUS Sabertooth Z77
- Processor: i7 3770k w/ stock fan
- PSU: Corsair TX750W PSU
- Memory: 2x4GB Corsair DIMMs
- Graphics: EVGA GTX 680

I would really appreciate any suggestions. Worst case scenario would be RMA'ing the mobo, and I don't really want to have to guess-RMA components.
 
Solution
jimmysmitty


There are some BIOS updates for the motherboard but none seem to address any fan issues so I don't think that will help.

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Vigdisar

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May 10, 2012
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OP w/ an update:

UEFI BIOS will show fan rpms on whichever four-pin the fan is connected to. The rpm read-out fluctuates between N/A (0) and about 1,000rpm in cycles of about 3-4 seconds.

So, the mobo 'knows' when the fan is connected to a four-pin. I'm assuming (although I haven't confirmed) that the rpm cycles are associated with the quarter-spins the fan does.

Also, haven't been able to reproduce fan functionality in about the past dozen or so tests. Whatever ounce of magic dust or whatever was causing the fan to operate perfectly on rare occasions may have run dry.
 
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al360ex

al360ex

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Oct 15, 2010
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Hello !

Your CPU is the not problem here. Do you have a custom cooler for your CPU, or is it the stock one ?
To me, it simply seems like your fan is DOA. Either RMA the whole thing your fan arrived with, or buy a new one.

Good luck,
al360ex
 
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V

Vigdisar

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Aftermarket fans, even some of the higher-end ones, are relatively affordable. I'm definitely springing for one (worst case scenario some other component needs to be RMA'd and I'll end up with a nice cooling fan anyway).

I'm just praying that the new fan doesn't show up and exhibit the same behavior. Every day is a ticking clock when it comes to Newegg's 30-day return policy. Is a stuttering fan that will sometimes function perfectly and at others just twitch until a reboot is performed typical of a fan hardware fault?
 
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al360ex

al360ex

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Yes it is. The only other thing I can think of would be a PSU problem, but if that was the case, then your fan would not be the only thing affected.
 
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ferny111

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If your cpu cooler has a molex connector (probably not since it is oem), if you have a 3-pin to molex adapter, or if your psu has a fan connector that will work with one of the ones on your cooler, try to just run the cooler (and only the cooler) off of your cpu. If you suffer the same scenario, rest assured, it is a hardware issue with the cpu cooler
 
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willard

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You can plug a four pin fan into a three pin header. The fourth pin is for fan control, and the fan will work just fine without it. The notches on the connectors should line up so there is only one way to connect it.
 
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skaz

skaz

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If I understand your first post correctly, you tested the fan on other four pin headers and still had the same issue?

For trouble shooting purposes update your BIOS and retest

If you still having the same issue then test another PWM fan on the headers and watch to see if it does the same thing.

Should be able to narrow the problem down to the board or fan at the least.
 
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ferny111

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Yeah, just try it out, and if it runs well, then it will has something to do with the pwm controller on your mobo, possibly be able to fix it through bios. If you get the same performance, then you got yourself a defective cooler, which is easy to remedy.
 
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Vigdisar

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Willard: The three-pin to molex that I have unfortunately has a plastic housing/sheath around the male three-pin, so a four-pin won't fit. I can see the notch line-up you mentioned though. I got excited for a second :p

I went ahead and tried a 3-pin fan. I don't have any other four-pin (PWM?) fans available. The 3-pin span up just fine. So, would that be a definitive PWM-controller issue then?

One last noob question: Updating the BIOS. The download would come from the mobo manufacturer, correct? The ASUS Z77 comes with USB BIOS Flashback. Would I just place the BIOS files (does it even work like that?) on a flash drive, and then flash it onto the motherboard? The manual says you just plug the flash drive into the mobo with the PSU connected and hold down the flashback button for three seconds.

I really do appreciate the help, guys.
 
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lilotimz

lilotimz

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asus motherboards usually are compatible with asus update utility where you can flash the bios easily without going into too much complications.

P..s you never told us if you had a custom aftermarket or the stock cooler..
 
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skaz

skaz

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Yeah a 4 pin fan is a PWM fan. If you tried a 3 pin fan and it started up and ran fine during your test then definitely sounds like the coolers fan is the issue. And yes you could be right it could be the PWM controller on the fan.

Can't comment to much on the Asus bios updating, I'm not to familiar with their flashback method. If the manual has a "manual" way to update the BIOS within the BIOS I would go that route. Be careful if you decide to update your BIOS as you can brick you mobo with a bad update.
 
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Vigdisar

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Sorry, it's the stock cooler until I buy an aftermarket.

Another update: Flashed the most recent BIOS from ASUS onto the mobo (surprisingly simple process http://event.asus.com/2012/mb/USB_BIOS_Flashback_GUIDE/)

Fan is still misbehaving. So, a 3-pin works fine on the CPU_FAN 4-pin mobo connection. BIOS Update didn't fix the issue. I don't have another system to test the stock cooler on (I'm on a laptop right now), or an adapter that would let me plug it into a molex connector.

Any other testing ideas? Also, does anyone with an NZXT Phantom Case that has the 200mm fan installed on the panel over the mobo have an aftermarket fan that they would recommend? I've read that some people had issues with aftermarket fans standing too far off of the mobo and hitting the 200mm.

Figured it might be easier just to ask rather than busting out a ruler and doing some ad hoc (and probably inaccurate) measurements.
 
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radeoniscool

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jimmysmitty

jimmysmitty

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There are some BIOS updates for the motherboard but none seem to address any fan issues so I don't think that will help.



For Asus, they have a tool in the BIOS (when in the BOS, press Esc, the select Advanced Mode then go to Tools and finally Asus EZ Flash) to do it. You download the BIOS from here:

http://support.asus.com/Download.aspx?SLanguage=en&m=SABERTOOTH+Z77&p=1&s=39

Windows version doesn't matter. Then put the BIOS rom file on a USB flash drive, leave the flash drive in the PC and reboot. Then go into the BIOS and follow my above instrucstions. Once there it may already be on the flash drive, if not on the left hand side you should be able to select it. Press Ok to read it then Ok again to flash it. Let ti do its job and it will reboot with the new BIOS installed.

But I am thinking it is either a bad fan or a bad mobo more than anything. If your PSU was bad, then chances of your PC posting and working normally would be very slim and since fans tend to only use a few watts, they might work while you wont get a post because the GPU and CPU use way more power than a fan does. Plus considering its a Corsair PSU, I doubt its bad since we mainly use Corsair at our shop (in our builds and we sell a lot too) and the number of DOA PSUs we have gotten is about one in a thousand so far. As well fans normally use the 12v rails for power as well (some use a resistor to drop it to 7v for quieter operation but still pulls from the 12v rail) as do many other devices (the CPU and GPU do as well and again use way more power than fans do).

As for the fan, a simple way to test it would be to hook the CPU fan up and then put a case fan to another header on the mobo, boot it up and see what happens to the second fan after multiple boots. If it spins up normally then it is the CPU fan that is bad, although I have yet to come across a stock fan being bad but it is still possible.

If both the CPU and case fan act the same way, again as said 3 vs 4 pin doesn't matter as the 4th pin is for PWM (basically a way to regulate the voltage to the fan by CPU temperature instead of always having 12v to it), then it would mean more than anything the motherboard is bad. I haven't had many bad Asus motherboards but it is still possible in the relm of computers (as is a CPU but thats the rarest of all components to be bad and would not cause the issue anyways).

So I would try that to narrow down your parts and find the culprit.
 
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Solution
V

Vigdisar

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May 10, 2012
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10,510


Sorry, the issued isn't really 'solved' persay. I just figured I would close the thread so as to let you folks help other users. I've ordered an aftermarket fan to see if the stock i7 fan was the issue (partially per ASUS's request from their customer support).

New Fan: http://www.newegg.com/Product/Product.aspx?Item=N82E16835214026

It's nothing snazzy, but it should do the trick and it fits my case / the LGA 1155 socket. If that doesn't work, the motherboard has a 5-Year warranty on it, so I should be alright.

Thanks again to everyone who commented for the help! ^__^
 
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