Precision 5680 with WD19DCS Performance Dock: Dual 4k Monitors?

Question

My company just got me a Precision 5680 with a WD19DCS Performance Dock. I plugged my two 4k 60Hz monitors in to the two DisplayPort outputs on the dock. Both cables from the dock are plugged into the two Thunderbolt 4 ports on the laptop and the lights are on. The laptop has Intel Iris Xe graphics as well as Nvidia RTX 2000 Ada Generation Laptop GPU. When I looked at display properties it says it was connected to the Intel Iris Xe. Every few minutes one or the other of the monitors goes blanks for a few seconds. I'm guessing they are losing sync as the monitors print out the resolution and frequency when they first connect and it does that after the few seconds of blank. I've read the specs on the dock and the laptop and I am thoroughly confused as to whether this combination should support 2 4k 60Hz monitors.

On my old Precision 5530 with the WD16TB these two monitors worked fine, so it would be very disappointed if a new setup is less capable than the old. I learned that apparently the WD19DCS is not a Thunderbolt dock which is really disappointing.

So should this combination support 2 4k 60Hz monitors?

Thanks.

ejn63 · Answer

I think you'll find it's a bandwidth issue -- you really need to use a Thunderbolt (WD19T or WD22T) dock for two 4K monitors.  Why did they supply a USB-C dock rather than a Thunderbolt dock?

DigitalMan43 · Answer

I think the WD19DCS was recommended because it uses two USBC cables to provide 210W of power for these laptops.

From here:

https://www.delltechnologies.com/asset/en-us/products/electronics-and-accessories/technical-support/dell_docking_compatibility_guide.pdf

This note describes it:

These Precision mobile workstations require more power than 130W, so when docked with the Dell Dock WD19 / WD19S, Dell Thunderbolt Dock WD19TB / WD19TBS or Dell Thunderbolt 4 Dock WD22TB4,
the workstations need to be plugged in externally for optimal operation. For the best experience with these Precision series mobile workstations, choose the Dell Performance Dock WD19DC / WD19DCS. The
WD19DC / WD19DCS dock comes with a dual USB-C connector that provides up to 210W of power delivery, so you no longer need an additional power adapter

As far as I know Dell for some reason doesn't have a Thunderbolt dock that can provide 210W.

DigitalMan43 · Answer

I do agree with you that it seems like the connection doesn't have enough bandwidth but from the link below, the supported resolutions for the WD19DCS are:

Max Resolution Details

Up to 5K: 5120 x 2880 - 60 Hz (Single Display)
Up to 4K: 3840 x 2160 - 60Hz (Three Displays)

https://www.dell.com/en-us/shop/dell-performance-dock-wd19dcs/apd/210-azbn/docks

robot15500 · Answer

I am having a very similar issue with a New 7680 running a WD19DCS. 2 Dell 4K monitors plugged in via DP to the dock. I routinly cannot get 2 4k streams, it regurally drops 1 to 1080p (or approximate). Latest graphics drivers and dock firmware. Any solutions?

Dynamicakhil · Answer

I struggled alot but ones I connected hdmi cable on right side of C port i sucessfully connected monitor with dedicated graphics card.

In my case 4k setting is on either side of port,not on couple of port which on other side.

Precision Mobile Workstations

Precision 5680 with WD19DCS Performance Dock: Dual 4k Monitors?

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