Hello Community,
i run a modified HP Z420. Modified since i put a AMD RX480, a Nvidia GTX 750TI and some USB3 Cards in it. To provide sufficient cooling it uses a custom water cooling loop.
My problem:
I connected all Fan headers to PWM fans (no warnings after POST), however the whole machine is pretty noisy, no matter what settings i choose in UEFI -> Advanced -> Thermal -> idle Speed.
Is there anything to get this machine quiet again?
CPU and GPUs never exceed 45°C under full load.
When i start the machine fasn are nice and quiet.
EDIT: i read that this might be due to the GPUs having/reporting no fan speed. Is there any workaround?
Specs:
Z420
Board: HP 1589
CPU: E5 2660
Ram: 8x8GB Samsung 1333 Mhz Reg ECC
GPU 1: AMD RX480 8GB
GPU 2: GTX 750TI
2x Inatek USB3 PCIe Card
A bunch of SSDs and HDDs 
Operating System is Arch Linux.
Really hope someone got a idea.
Cheers