Chassis fan RPM oddity (ASRock Z97 Killer)

[Keizer]

I recently started using the AIDA64 remote sensor so I can monitor stats during game play on my Ipad.  I have the Asrock Z97 Killer mobo.  I have my CPU fan, and chassis fans set up in the bios to throttle up and down depending on CPU temp.  Basically anything 37C and below my fans will run at 40%.  When my CPU temp raises to 38C and above, all the fans increase in RPM to 65%.  So when I'm at my desktop doing basic stuff the chassis fans turn in the 800 RPM range, and while ganing they throttle up to the 1200 RPM range. 

 

Anyway, today while gaming I noticed chassis fan 1 and chassis fan 3 would occasionally show 19,640 RPM on my ipad.  I have all my favorite stats also showing on my desktop using OSD.  So I backed out of my game as fast as I could before my fans throttled back down.  The OSD chassis fan readings also displayed this 19,640 RPM a few times.  Once the chassis fans throttled back down to 40%, RPM readings were stable only fluctuating slightly up and down like they always do.  My CPU fan RPM as well as my GPU RPM were fine and stable the whole time.  

 

What could cause this?

[Fiery]

I suppose it is a temporary fan RPM readout issue of the motherboard sensor chip. On your system AIDA64 simply reads the fan RPM value out of the sensor chip, without converting it. So if it shows 19640 RPM, that's the value that the sensor chip provides.

[Keizer]

I kind of figured it was mobo specific.  Peculiar that it doesn't happen when the fans are running at the lower 40% range.  

[Metallon]

Mate I have exactly the same issue but on Asrock X99 Extreme4.. It happens exactly the same thing. When chassis fans spin at lower than 1000 rpm, the readings are correct and only go +-20. If I set them to spin higher than 1000 rpm the programs (all of them including bios readings) start reading spikes. The most usual spikes are either 0, +1000  than normal (for example 2130 instead of 1130), or 19640.  

 

I want to underline some things. I have 3 chassis fans that came with my case (Zalman R1). I have plugged the back fan on the Power Fan slot of the mobo and the 2 other fans on chassis fan 2 and chassis fan 3 slots of the mobo. The false speed readings occur ONLY for the fans that are plagged on chassis fan 2 and 3 slots. The one that is on the Power fan slow readings are always correct with no strange spikes.

 

At this point I have a question which is the only thing I can think of that MAY have cause any dmg to the sensors. When I installed my mobo I did apply some pressure cause I had forgotten to put the very right side of the mobo standoffs. So as the right side of the mobo was hanging in the air (about 5 cm of mobo panel width in the air), the mobo did bent when I was plugging the ATX PSU cable for example which goes to the very far right side of the mobo.. So if that bent might have caused any problem to the sensonrs... But again, would it harm ALL the sensors? How possible is this? The 2 fan slots I use are not even close to each other.

 

 

So just in case I'd like to ask you if you "mistreated" your mobo when placing it in any way like the one I mentionted without being sure that it could cause such a problem. Also you said your fan 1 and 3 have this behaviour.. Do you have any fan plugged on slot 2 which works fine or you don't have any fan there that's why you didn't mention it? Other than that our problems are identical so I don't understand why you think it is mobo specific problem. If you found any fix I'd like you to share with me.