CPU Fan always runs Full Speed

[wrighla]

From boot up to shut down, my CPU fan runs at full speed.  There is no variability.  O/S power settings do not affect the speed.  It is extremely loud all the time.  Otherwise the computer has been flawless and fast for several years.

It started after very briefly unplugging and plugging in the fan to the motherboard while the pc was on.

I have tried every setting I can think of in the bios and have the bios up to HP Assistant's latest version of 8.21.  System Board is identified as 2AD5 1.03.  Processor is Intel Core i7-3770 CPU @3.40GHz.

Do you have any suggestions for how I can correct the problem?

[TheOldMan]

This statement might be the clue "It started after very briefly unplugging and plugging in the fan to the motherboard while the pc was on."

First off, why was that done?

Second - it might have damaged the CPU and it is telling the sensor that it is running hot.

Download HWMonitor then run it to find the CPU temperatures.

http://www.cpuid.com/softwares/hwmonitor.html

[mdklassen]

> It started after very briefly unplugging and plugging in the fan to the motherboard while the pc was on.

Presumably, that fan has 3 wires -- two for power, and one for a "sensor" (or "speed-control").

It's possible that the unplugging has damaged the "sensor". 

Replace the fan.

[wrighla]

No doubt the unplugging and plugging the fan back in (roughly uplugged for 3-5 seconds) caused the fan to run at full speed.  I'm just trying to solve the issue without throwing the otherwise great, pc away.  Not sure it helps but the why was because I heard a slight fan noise (possibly dust build up rubbing) that I was trying to isolate between the 3 fans inside the case.

Thank you for the temp tool idea.  It reports Intel Core i7 3770 temperatures across 4 cores with min values varying from 60-71 F and max values between 102 and 111 F.  A quick google search appears to show I'm in a reasonable range.   I will also add that under Fans PWM CPU percentages show 32%.  System Fan 1 22%.  System Fan 2 49%.  And the problem System Fan 3 shows 100%.

[wrighla]

@mdklassen

Yes, the fan and plug has three wires.

To be clear, do you believe the sensor prong in the cable connector is broken or that the fan itself houses a sensor that could be broken and replacing will rectify?

[TheOldMan · Accepted solution]

The CPU temps appear to be OK, so lucky.  Next would be to try a new fan.  If this is a normal CPU cooler, it should fairly easy to find a replacement.  Since that is an Intel, they use Intel fans with standard specs, i believe.

[mdklassen]

> To be clear, do you believe the sensor prong in the cable connector is broken or that the fan itself houses a sensor that could be broken and replacing will rectify?

The correct way to answer such a "compound" phrase that contains the word 'or' is to answer 'yes'.  🙂

Hopefully, the "breakage" is contained within the fan assembly, or within the connector that connects to the 3 pins on the motherboard -- not within the 3-pins on the motherboard.

At this point, replacing the fan is least-expensive thing to try.

[wrighla]

Thank you both for generously offering  your time and advice - I am taking your advice right now and searching for the replacement part.  I will post back results.

[wrighla]

I replaced the fan with the intel replacement fan and it is running normally and QUIET 🙂

I had no idea the fan was anything more than a motor.

Thank you both again!

Lloyd

[DiscoingGD]

I have the same problem, but caused after a BIOS driver update. I've had this computer for 3 months with no modifications, except mounting an additional fan on the 120mm bracket up top, plugged into the LC_PUMP on the motherboard.  It's been running fine, fan and all, except occaisionally it would give BIOS error beeps (3 long, 3 short). I read that a few people had this problem and that downloading the BIOS driver update would fix it, so that's what I tried to do. When I restarted, the fans now run at full speed, even at idle when temps are cool. They always ran quiet before, even while gaming it rarely got this loud. Now, a mistake on my part is that I downloaded an extra driver, as it was on the list of drivers for my product, but I didn't notice that it had a different motherboard ID.

I'm not sure if the wrong driver went through and messed this up or if the correct driver overrode that but still caused this issue. If it is the former,  I need to know how to revert back my BIOS so that update no longer affects me? If it is the latter, I need to know why it messed with my fan speed and how I can fix it? Any help is appreciated!