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Walker M
Copper

Inspiron 7720 fan will not turn on, laptop shuts down

Dell Inspiron 17R SE 7720, Windows 8.1.

Summary: Laptop shuts off when fan does not start and gets too hot, cannot force fan to start.  Seems the only way to control fan speed and activation temperature is through BIOS, which I can only access through F2 during loading, and which only displays on the non-working laptop monitor and not on the external monitor, and is therefore impossible to see and configure.

 

This laptop has, for some years, had a noisy yet effective fan that has until recently provided adequate cooling.  Now sometimes the fan will fail to start up when the computer heats up, resulting in a complete and automatic shutdown.  This does not occur when the fan has started up and begun to cool the computer; when the fan is operating everything works great, but lately it has not been starting when it should.  Thus far I have been unable to decipher what requirements the laptop needs in order to turn the fan on, as temperature seems to be no reliable indicator, and the CPU and memory usage vary inconsistently between the fan-on and no-fan scenarios.

I have removed, cleaned, and replaced the fan.  Since I did that the computer has still exhibited the inconsistent behavior wherein if the fan starts everything is fine, but sometimes it will not start and the computer instantly shuts off at a certain heat threshold.  

My system cooling policy is set to Active both for battery and plugged in.

I have researched methods for manually altering the fan behavior through the UEFI BIOS.  I followed the instructions in the Dell Support article indicating how to access BIOS for 8.1.  I first tried the method wherein I tap F2 as the system starts up which seems to successfully engage the BIOS, but this has brought about another problem, as my laptop screen does not work.

My screen is compromised such that I have to use an external VGA monitor.  The laptop will not force picture onto the external display in BIOS, or during any other arrangement before the OS has loaded.  I attempted to manually induce a switch with Fn + F1, but this does not force a change in a pre-OS setting.  I have always had my screen projection set to second screen only, but have also tried duplicate, and the BIOS screen was not duplicated.

I thought to follow the instructions for navigating to BIOS through the start menu, also as described in the Dell Support article.  I navigated to the Charms Bar with Windows Key + C, clicked power, and held the Shift key while selecting Restart.  I then chose the Troubleshoot option, and next the Advanced Options.  From that point there is no option to select UEFI Firmware Settings, which seems to be a vital step in the process.  The other five options are present, but this one is not.  I then tried selecting instead Windows Startup Settings and restarting, but this requires pressing F2 during start up, which, again, results in a BIOS menu that I cannot see on my external monitor.  I have also tried closing my laptop screen while in the BIOS menu, but this does not force the image to the external monitor.

I have downloaded Speedfan and HWMonitor, both of which are helpful in viewing temperatures and the like, but neither of which is able to detect or control the fan. 

Is there some way to force the pre-OS BIOS image onto my external display?  Alternatively, is there some way to force my fan to turn on without accessing BIOS?

Thanks for any help

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3 Replies
FAISTECH4U
Bronze

Re: Inspiron 7720 fan will not turn on, laptop shuts down

YOU MUST CHANGE YOUR LAPTOP FAN

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Walker M
Copper

Re: Inspiron 7720 fan will not turn on, laptop shuts down

Thank you for your loud suggestion.  I have tried a new fan and am experience the same problem.

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ejn63
Diamond

Re: Inspiron 7720 fan will not turn on, laptop shuts down

That would leave the temperature sensor as the faulty part -- unfortunately, the only way to replace it is to replace the system board.

 

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