OptiPlex 380 fan speed control failure in Windows 10 following a wake-up from sleep
Production date: 5/2011
Windows 10 SP1
Chipset driver 126.96.36.1996
System boots fine and fan speed operates to maintain CPU temperature as expected by CPU temperature table in BIOS.
Once the system goes into sleep and awoken, the fan is locked at minimum speed irrespective of CPU temperature hits maximum and pegs out on thermal throttle.
Can anyone else duplicate it?
Some CPUs do not get hot enough to ever need to spin the fan above minimum under ordinary conditions and in that case you'd need to block the air intake in front of the PC to duplicate it. Confirm that CPU fan ramps up with loaded up (such as Prime95) and airflow blocked off.
RE: OptiPlex 380 fan speed control failure in Windows 10 following a wake-up from sleep
Dell hasn't tested the OptiPlex 380 for compatibility with Win 10 and isn't offering any drivers or support for that OS on this model. So you're on your own here.
First thing would be to go to Intel's download site and use their wizard to scan your system for suitable chipset and video drivers that are compatible with Win 10. See if updating those drivers helps with the fan problem.
Also go to the manufacturer's site for your add-in video card (assuming you have an add-in video card) and see if they have a Win 10 driver for your specific video card....