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CPU fan not detected - error 511

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HP Pro 3515 MT
Microsoft Windows 10 (64-bit)

Since upgrading from win 7 pro 64 bit O/S to Win 10 Pro 64 bit (c.10 months ago) I have experienced the manifestation of a number of errors with respect to boot/start up and Live Mail shut down - all persist to this day. The most annoying is the apparent "CPU fan not detected error 511 press F1 to boot".

Pressing F1 to boot works every time and the machine, from this point, runs well. I use WiFi for my internet connections and this works fine too.

However, there appears to be nothing wrong with the fan, i.e. it spins absolutely fine - that is, once it kicks into life after hitting the F1 key. It never misses a beat. If I do a restart or a shutdown, when the HP Logo pops up it is followed by the eror message: a little earlier the restart did not provoke this error message, but recently it also resulted in the now familiar message being displayed.

Hp diagnostics - included on my machine - indicates I should run a hardware check. Sadly I do not have the essential option to do this as it was included in a bios update for Win 7 which I missed and have since upgraded to Win 10 and I am unable to run the hardware test as a result. Current BIOS version is 8.17 it should be 8.20 according to latest HP data (for, specifically, Win 7 - not Win 10). My instincts tell me updating the BIOS now will cause issues. The fan meantime runs perfectly quietly and is very clean - i.e. dust free and, in any event, the machine is under two years old - at point of delivery - 4 months after it was purchased - but that's another story. Other research suggests I replace the CPU fan/Heatsink assembly, but at £176 inc del. it is a no go as it is equal to about half the cost of the complete machine when I bought it! There has to be a better way - can someone help please?

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You may have to replace the CPU Fan,


511-CPU, CPUA, or CPUB Fan not


CPU fan is not connected or may have


1. Reseat CPU fan.

2. Reseat fan cable.

3. Replace CPU fan.

I am a HP Employee
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I am not familiar with the HP Pro 3515 MT, but on other products (like Workstations), the fan speed is detected by the BIOS, before the OS is loaded.  Upgrading from Win7 to Win10 should not cause fan failures. 


Vanninman wrote:  "However, there appears to be nothing wrong with the fan, i.e. it spins absolutely fine - that is, once it kicks into life after hitting the F1 key." 


The fan should be spinning when the system is powered up.  If the fan is not spinning, then the BIOS will give this error.  If the fan is not spinning until you hit the F1 key, something is wrong.


Sometimes fans are slow to spin up, and give this fan detect error.  Sometimes fans get clogged with dust, which causes them to stop spinning.  Or if the fan connector is unseated, then the error will occur (not in your case, since the fan spins after an F1 key press).  Usually fan failures are fixed by replacing the fan. 

I am an HP Employee.
My opinions are my own, and do not express those of HP.

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I have had the same problem since Windows 10 installed the last patch.  It was fine before that.  I have an HP 110-414.

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I agree with Dan, a failing fan that does not reliably start up appon receiving power is the most likely cause



the fan (if failing) has to start sometime,.......and the fact that you noticed it during a windows update doe not mean it is the cause

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