yesterday evening my CPU fan started to do crazy stuff. Currently it only knows "normaly working" and "100%".

For the system, it is a quite new medi-core system, configured/build by myself and worked like a charm for 2 month.

The interesting system parts:

  • Mainboard: Asus M5A97 Evo R2.0 AMD 970 So.AM3+
  • CPU: AMD FX-Serie FX-6300 ( Boxed )
  • Cooler: Scythe Katana 4 ( replaced box fan/cooler unit )

What I did:

  • SpeedFan/Hardwaremonitor - try to set fan speed manually
  • Enable/Disable Cool'n Quiet
  • Manually set fan speed in Bios ( not working )
  • FW mainboard update/flash ( not that I thought it would help, bc. system ran fine before an the changelog had nothing about fan controls in it )

As I said earlier, the FAN has 2 modes: normal mode, everything works normal, can set Fan speed by software/bios and cool'n quiet works together with win 7.

and 100% mode, wich starts without any specific reason. Plus a restart or/power off/on does not solve the 100% CPU Fan. In 100% mode I am not able to control the fan speed whatsoever ( speed fan/ asus speed/ bios... )

Sometimes it goes to normal for no specific reason ( system was unzipping a 25gb file and it went to normal, system was idle on win desktop and it went to 100% FAN again )

CPU stress was never above 50% and even while using a prime/stresstest it never went above 45 deg ( normal/100% fan mode - in normal it slowly climbs up to rpm max... )

The CPU tempretature looks "good", BUT it seems to be to low. GPU/Chasis temprature display reasonable values ( 20-30 deg ) but CPU temprature is around 10 deg - when my room temprature is around 20 deg... and as I did not build a peltier element into my pc - that is strange.

Plus, if the regulation would work correctly the fan should nearly stop/ 0 rpm on me.

So, I am wondering: is the fan simply broken? Or do I need to check CPU/Mainboard issues as well?

Currently I hope for a broken fan and try to replace it with the boxed/bad fan that was in the package until a replacement is delivered.

  • Have you tried BIOS update or changing temperature threshold on BIOS configuration? – emirjonb Aug 24 '15 at 8:15
  • @emirjonb yes, as stated above I updated the mainboard firmware. Any setting of threshold/manual override and so on is only working in "normal mode", if it goes to its 100% mode, it wont listen to any of those values – Najzero Aug 24 '15 at 8:19
  • how many pins does the fan have 3 or 4? – emirjonb Aug 24 '15 at 8:25
  • has a 4 pin pwm - correctly connected ... and worked for over month, even during the recent heatwave and around 30-40 room temp. – Najzero Aug 24 '15 at 8:31
  • I think you should try a new fan, you can use your boxed AMD fan, and a BIOS restore to Default (just in case) – emirjonb Aug 24 '15 at 8:46

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