HP Z2 G9 — CPU Fan starts spinning at full speed even if only one or two cores are at 100% usage

[wrobelda]

I have a Z2 G9 Tower running a Proxmox supervisor and several VMs on it. If any VM puts its allocated CPU core to full use, the CPU fan starts blasting full speed — even if the rest of the cores remain idle and a total CPU usage remains low (3-5%). As soon as I stop/kill the process causing this, the CPU fan speed drops immediately.

The BIOS therefore ties CPU fan speed to the CPU usage, and it does a very bad job at that. Why can't HP be like everyone else and use CPU temperature for controlling the fan speed? It's no surprise there's so much negative feedback on this Workstation's fan behavior.

In any case, this is a major issue as the CPU temps overall are very low (in 30C), the total CPU usage is very low (3-5%), yet the CPU keeps spinning like crazy. Can this be reported to relevant team and fixed? 

[DGroves]

if you are pushing two (or even one core) cpu cores to 100% load for more than 10 seconds expect the cpu fan to go to full speed this is normal behaviour on any modern system, and is not unique to HP

even a single core generates impressive heat in a small area on the cpu die

i would start looking into why your VM is causing a 100% load, a common cause is that your the HP system's resources are unable to meet the VM's demands

https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.monitoring.doc/GUID-5F8147A1-6416-4...

[wrobelda]

VMs use 100% when they are expected to, nothing odd here or unusual in my case.

Assigning all 16 cores to the VM and distributing the load evenly across all cores changes nothing. And that's not a surprise, because I did not have those VMs pined to specific cores, so they were distributed evenly previously anyway. 

The fan spins even when the VM usage is moderate and as soon as the total CPU usage is over ~7% and while none of the cores is particularly loaded, so my previous conclusion regarding the BIOS not averaging the load was wrong . Note that this happens when temps are still in mid 30s. 

Even switching to "Quiet" performance profile changes nothing.

I am leaning towards getting an external PWM USB controller and an aftermarket CPU fan to sort this out. HP using proprietary PWM control which are not accessible to the operating system is not very "workstation"ey, from a professional standpoint. At least a BIOS setting allowing to expose those would be nice.