I'm not sure what you're talking about.
Thermal settings in Z800 BIOS does not have anything to do with cpu fan rpm.
They just increase case in/out fans speed. Fan speed is controlled by CPU onboard temperature sensor.
Even at thermal set to 3, the workstation is louder than any comp we have in the room and tunning hotter than any.
In past 20 years I have build all machines by myself.
Currently I have i7 980X running around 50C under max load with just a small wind humm from fans.
I have build machines that last for a decade and non of them had any thermal issues, so I kind'a have ideas how system should be bult to run silent, reliable and for a very long time under heavy load (3ds max/Maya rendering).
Manufacturing of HP heatsinks looks horrible. It looks like garage bult piece of hardware and they cost more than any heatsink on the market. I am dissapointed, and you can say whatever you want it won't change my perception.
Cheers!