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Discussion Starter · #1 ·
Hey guys, i've just built a new rig and set it all up
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I really need to ask...

With my motherboard (M5a97 evo R2.0) When i look in the bios on the fan speeds (hooked up to the mobo) The rpm fluctuates. When it's set on standard or turbo etc... all of the fan speeds change every second from say 600rpm then can shoot up to 20.000, varying wildly. If i set it on silent they all stay at 600 rpm, but if i set any other go completely mad.

A video i found like i have (but this guy had it happening to one fan - all 3 do this to me)
Is this normal? I was reading that it could be a bad sensor?

I also noticed when i got the motherboard out of the box, that the bag was unsealed and fingerprints on the CMOS battery!

Any help would be great!
 

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I'd probably return the board or RMA. could be a sign
 

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Discussion Starter · #3 ·
Yeah, i wasn't sure what to do as i put this together yesterday. The fans themselves i dont think change speed but in the bios it goes crazy. It made me wonder as there were fingerprints on the Cmos battery and the anti static bag wasn't sealed. I might have to contact for a replacement, which i didnt really want to do with it all plugged in.

The huge rpm changes makes me think i might have to, if it isn't normal :s
 

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Discussion Starter · #5 ·
Hmmm, i'll contact them i think. I looked at the board ( i was even super careful and used latexy gloves) and saw the prints on the battery (looked straight away as often read about looking there) but thought i'd try it (the non sealed bag worried me too) It was new, full price. I only noticed when i checked in the bios the crazy fan speed readings :S
 

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My m5a99x evo R2.0 does this but only with certain fans. One of my corsair h100i stock fan regardless of which header its connected to and my other sp120 high performance fan I use to use on my old 212 evo. Now I have my h100i fans connected to a four pin splitter with my one h100i fan that has always reported correct rpm speeds connected to the split that reads the rpms. I replaced all my old three pin xigmatek fans with bitfenix four pin 1800rpm fans and they all report correct rpms. I use my fx-8350 stock fan on my vrms and it reports the correct speeds as well.

All the fans operate perfectly fine. I just think its some random bug with certain fans. Unless its doing it with every single fan, you probably don't need to rma. You can always click on the rpm readout in your bios and click disable to disable rpm monitoring.
 

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I bought a brand new Sabertooth X79 a few weeks ago, and if i leave HWMonitor open for a day or 2, i will notice it shows the fans hit 60k rpm not normal i don't think, but dealing with ASUS RMA over is silly, i spent almost a month RMAing my Maximus VI Extreme. It sat delivered at ASUS for 2 weeks before they shipped a new one.
 

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Discussion Starter · #9 ·
Hey guys, sorry for the late reply. Been a bit hectic! Hmmm, that is interesting, so it could be a bug? I noticed it only when i changed the fan speed from silent(silent is registers as normal rpm - normal, turbo etc... it shoots up randomly every second to all 3) and then later checked bios it reported that. It happens to all 3 of my case fans, rather than one (the fans are Fractals stock fans with the case)

The reason i was thinking of replacing if it was a fault was because i purchased from Amazon, sois in warranty with them, rather than a 6 week wait. Thanks for the replies though. So what do you think i should do? I was also thinking about the fan speed going mental aswell as the board being unsealed and fingerprints all over the battery. Should i just live with the fan speed readings going a bit crazy? Again thanks for all of your help!
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It could be the brand of fan you are using. Not all manufacturers use the industry standard. Is it a Corsair fan? How do you have the fans hook up? Do you use a splitter cable?
 

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    The erratic readings can also happen if the fans are running very slowly and being controlled by voltage rather than by a separate PWM control lead (4-lead vs. 3-lead fan).
 

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I have a Gelid fan that does that(the fan does it not the board in my case).

Voltage vs PWM should not actually cause this I have had voltage controlled. fans for years without this kind of issue.

Very low speeds can cause this as well for sure on some fans.
 

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Sounds more like a broken sensor to me.Run HWmonitor for some time check if there is no anything what would reach over 160c.Not long a ago had same fan problem from funded out that broken sensor was the problem.Got my money back from Asus and got free upgrade
 

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Quote:
Originally Posted by Nukemaster View Post

I have a Gelid fan that does that(the fan does it not the board in my case).

Voltage vs PWM should not actually cause this I have had voltage controlled. fans for years without this kind of issue.

Very low speeds can cause this as well for sure on some fans.
The problem is that the fan's PWM signal is supplied by the fan's supply voltage. In PWM mode, the fan has full 12v all the time (with a four lead fan), and the speed is controlled by the fourth fan lead. But in voltage mode, the voltage to the fan is reduced, and this can cause the PWM signal from the fan to diminish towards the threshold of detection for the motherboard, thus causing erratic readings. And if voltage is dropped further, the RPM reading will drop to zero, even though the fan is still spinning.
 

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Discussion Starter · #15 ·
Hey guys, the fans i'm using are the stock fractal design ones that came with the case (they are a 3pin header) It's odd that if you run it at low speeds it can be erratic, when the lowest speed seems to keep them all at 600rpm, any other setting and it goes nuts (20.000, 60.000 every second changing from one to another of the 3 fans) If it were a broken sensor i could contact amazon and hopefully get a replacement, i was just worried as its a new motherboard and this was acting very odd. Thank you for all of your replies guys! (i mainly wanted to try and replace/sort it sooner rather than later as i'd much rather deal with amazon, than Asus-in fact i was this close to going for a gigabyte board after reading rma's with asus)
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