The MB is an old Asus Sabertooth X79 purchased in 2011.
System PSU is an equally old Corsair HX850.
GPU is an Evga GTX 480
Case is the only new hardware component, a Fractal Design Define C
OS is Windows 10 Pro, clean install, up-to-date
BIOS are up to date (v.4701)
BIOS have been reset to default settings
Device Manager shows no errors
System Panel power connectors are connected correctly.
There are two case fans, the CPU fan, GPU fan and PSU fan. On the mother board itself there is also a I/O cover that has a fan and there is a fan over the PCH.
So the weird thing that is happening is that one of the case fans (the front), the I/O fan, and the GPU fan continue to run after the system is shutdown. (This is a real shutdown. CMD: shutdown /s. Not just pressing the power button.) The CPU fan doesn't continue to run but it will jerk every two seconds like it's trying to start spinning but can't quite overcome its own inertia.
If I leave the computer turned off but plugged in, the fans continue to run…forever.
The fans also continue to run if I unplug the PSU and flip its power switch to 'off.'
They continue to run if, after unplugging the PSU, I press the case power button in an attempt to drain the system capacitors.
Under these conditions they will keep going and going for 5... 6...7 minutes.
Eventually, they will stop because, well… the first and second laws of thermodynamics can't be denied.
I've plugged both the CPU fan and the front case fan into different fan headers on the board. No change in their behavior.
So what gives? The Google says that this is an out-of-date BIOS issue for this MB but I’ve addressed that. Any other suggestions?
The motherboard has a standby LED that remains lit after shutdown, indicating the the motherboard at least doesn't think the system is fully shut down. How can I convince it otherwise?
Thanks in advance for any insights. Have a safe and happy New Year!
System PSU is an equally old Corsair HX850.
GPU is an Evga GTX 480
Case is the only new hardware component, a Fractal Design Define C
OS is Windows 10 Pro, clean install, up-to-date
BIOS are up to date (v.4701)
BIOS have been reset to default settings
Device Manager shows no errors
System Panel power connectors are connected correctly.
There are two case fans, the CPU fan, GPU fan and PSU fan. On the mother board itself there is also a I/O cover that has a fan and there is a fan over the PCH.
So the weird thing that is happening is that one of the case fans (the front), the I/O fan, and the GPU fan continue to run after the system is shutdown. (This is a real shutdown. CMD: shutdown /s. Not just pressing the power button.) The CPU fan doesn't continue to run but it will jerk every two seconds like it's trying to start spinning but can't quite overcome its own inertia.
If I leave the computer turned off but plugged in, the fans continue to run…forever.
The fans also continue to run if I unplug the PSU and flip its power switch to 'off.'
They continue to run if, after unplugging the PSU, I press the case power button in an attempt to drain the system capacitors.
Under these conditions they will keep going and going for 5... 6...7 minutes.
Eventually, they will stop because, well… the first and second laws of thermodynamics can't be denied.
I've plugged both the CPU fan and the front case fan into different fan headers on the board. No change in their behavior.
So what gives? The Google says that this is an out-of-date BIOS issue for this MB but I’ve addressed that. Any other suggestions?
The motherboard has a standby LED that remains lit after shutdown, indicating the the motherboard at least doesn't think the system is fully shut down. How can I convince it otherwise?
Thanks in advance for any insights. Have a safe and happy New Year!