I got my dock replaced for the second time and it's finally working as it's supposed to! No more that crazy 100% speed all the time. In fact I'm using if for a few days now and I do not saw it go to 100% a for a single time... So silence! I've checked the firmware version of the new dock and it's the same one as my old ones, so it was definitely a hardware issue. The only odd thing is that the service tag of the replacement dock that they sent me is not being recognized by Dell at all... When I search for it it says that it does not exist. I've tried twice to private message @DELL-Cares who was in contact with me and do not heard back from them... I'm afraid of that because if something goes wrong with this one how will I ask for my warranty?
Maybe a little late to the party here, but I use this dock on my desk: https://www.dell.com/en-us/work/shop/accessories/apd/452-bcyt and it never makes any noise at all. Can handle two 4K screens at 60Hz and a third 4K screen at 30Hz if you want to go that far.
@AndrewJDawson what you posted is true, but it's also true that the D6000 relies on "indirect display" technology called DisplayLink for the first two displays that get attached. When 3 displays are active, whichever display is on HDMI uses a native GPU output via DisplayPort Alt Mode, but that's only available when using USB-C to connect to the system. The reason I mention this is that DisplayLink comes with some drawbacks that can be significant for some people's use cases. I wrote about those in detail in the post marked as the answer in this thread. The WD19 family of docks, like most docks, instead use native GPU outputs for all attached displays.
The D6000 can also only supply up to 60W to attached systems, whereas the WD19 and WD19TB can supply up to 130W depending on the attached system and the power supply connected to the dock, so the D6000 will not adequately power all of the same systems that the WD19 family can. Some systems like the XPS 15 when attached to a 60W power source will respond by dramatically reducing their battery charging speed and CPU and GPU performance, which obviously isn't ideal.
I'd like to second what @jphughan said about the D6000. IIRC years ago I had the same conversation with him about it when I was looking for a new docking solution after Dell laptops stopped shipping with e-port slots.
The D6000 reminds me of those various "USB Video adapters" that are out there for ~$40. They're fine for emergencies, but I wouldn't use that video-over-usb technology for any heavy lifting.
I'm a bit surprised that @AndrewJDawson is having such luck with 4k displays and the D6000. For the few weeks I had a D6000, I couldn't get what I consider acceptable video performance with two 1080p screens, let alone 4k. The lag was really noticeable when scrolling through large excel spreadsheets or simply dragging Explorer windows around. It reminds me of using VNC to control a remote system.
Changing the Windows 10 Performance settings to "low" was a workaround but in the end we bailed on the D6000 and went with the ill-fated WD16's that had their own share of problems.
We've now since gotten rid of all our WD16's and we're mostly happy with the WD19s other than these fan noise issues we've seen on several of them.
@2000Gatekeeper I got it fixed by getting a replacement from Dell. I compared the firmware versions and both docks have the same one, so it's definitely a hardware issue. This was the second replacement that I got from Dell... The first one came with the same issue... So I told them about it and they tried some beta firmware with no luck untill they decided to send me another one again and this time it worked!!!