WD19 dock doesn't output 4K 60Hz on HBR3 system

So the Inspiron 7506 isn't explicitly listed in the Dell laptop / Dock compatibility list. It is a USB-C laptop though so it can use the WD19 dock with limited functionality. In this case I assume it might be using HBR2 or possibly only a single HBR3 lane (but I don't know enough about this stuff).

Interestingly though, the Silver Inspiron 7506 hdmi output is listed as hdmi 1.4b in the specifications (so should only output 4K at 30Hz if used directly), but in my case it can output at 60Hz, so that is a silver lining at least. I can use the laptop hdmi port directly for 4k at 60Hz until I find a suitable dock replacement.

Looking over other posts in this forum, it looks like the WD19 HBR3 4k 30Hz support issue is a relatively common issue, with both officially supported and non supported laptops:

https://www.dell.com/community/Latitude/WD19-Docking-Station-Compatibility/td-p/8032431

https://www.dell.com/community/Inspiron/Dell-7706-with-WD19-UHD-support/td-p/8066190

https://www.dell.com/community/Latitude/Latitude-7520-WD19S-P2721Q-4K-30Hz-only/m-p/7991739

https://www.dell.com/community/Monitors/U3219Q-Surface-Pro-7-WD19-WD19TB-4k-at-60hz-issue/td-p/7540671

https://www.dell.com/community/Latitude/Attn-J-P-Hughan-WD19-4K60Hz-issues/td-p/8064030

Seems like technically 4k 60Hz should work for HBR3 systems using the WD19, but for whatever reasons sometimes they don't. After reading the above threads, I am hopeful for a future firmware fix/improvement for the WD19, In the meantime I can try some of the suggested workarounds.

Thanks dcs, I previously gave up looking into this issue, but checking again now, it appears to be running at 60Hz.

I am not sure if the quality is worse. It looks pretty clear for my setup, but I have only done a quick test. I will have to do a more thorough comparison.

Strangely the monitor OSD Display Info just says "2160P" (doesn't show the Hz) when plugged into the dock, but explicitly says "3840x2160, 60Hz" if I plug it into the laptop hdmi.

The Win11 Advanced display properties say "YCbCr420" Color Space at 60Hz when using the dock, but "RGB" Color Space at 60Hz when plugged into the laptop. Maybe the YCbCr420 color space is causing the image quality issues for your setup?

I will have to get a DP cable so I can try and run both my external monitors through the dock. As you indicated, plugging monitors directly into the laptop does kind of defeat the purpose of the dock.

Thanks for taking the time to reply to my issue with your solution!

Good point on the color format. I confirmed the WD19S HDMI port is YCbCr420, while the 7420's HDMI port is RGB (both 8 bit).

Seems to indeed be the issue, but I can't find a way to fix it. In the "Intel Graphics Command Center", I get a lot of choices for color format and bits when plugged into the laptop's HDMI port. If I switch that to YCbCr420, the built in HDMI port looks as bad as the dock (blurry/odd colors as described in above post). Switching back to RGB fixes it.

The rub is when I plug into the WD19S, those settings choices go away (no longer can change color format, etc.). So I don't see a way to move the hub output to RGB which would likely fix my problem and allow me to only plug in one wire (hub USB-C), vs. two (+HDMI).  Any ideas?

From the Intel Graphics Command Center, I see this interesting bit of info...

When directly connected to the laptop it shows as "HDMI", in the Information tab, and allows color format changes in the General tab:

Yet when plugged into the HDMI port in the WD19S, the app things it's a DisplayPort!  And any color format settings options go away.  Seems the dock is doing some internal translation/shenanigans which the PC/Intel Drivers mis-interpret.  Given this I may be SOL

Okay, I think I've got mine working now. Anyone trying to use a cheap 4K TV as a computer monitor from a WD19S hub via HDMI on an HBR3 system may benefit from this (make sure you set to game / PC mode on your TV to get the best monitor setup and lowest latency without any of the TV's image smoothing algorithms turned on).

I noticed in the hub specs that HBR3 systems max out at a single external 4K@60Hz, but can go to 8K@60Hz (or dual 4K@60Hz) if using Display Stream Compression (which I think only applies to DP, not HDMI).  Since this WD19S shows it's HDMI port as DP to Windows, I thought this may free up some bandwidth to allow RBG color format and fix my blurrines.

Oddly, many Dell systems don't enable DSC by default, but I found an article on how to enable it on my 7420:

https://www.dell.com/support/kbdoc/en-us/000197102/how-to-enable-display-stream-compression-on-latitude-precision-and-xps

Doing so and re-booting now defaulted the WD19S's HDMI port to RGB color format when running at 4K@60Hz.

I still can't "change" the color format, but the extra bandwidth popped this over to RGB and now I'm crystal clear identical looking to the laptop's HDMI port.

I've found trying to enable HDR is a waste of time and make the daily "office PC" view actually worse.  Best setup for my eyes is 4K@60Hz - RGB -  8-bit - SDR.

Sad that a user has to do all this digging instead of it just working as expected out of the box...

Thanks again dcs,

Enabling DSC as above has worked for me too, but after playing around with the Intel Command Center a bit.

After first enabling DSC and restarting my pc, it was outputting 10-bit RGB 30Hz through hdmi, and YCbCr420 30Hz through the dock (I think it also showed 10-bit, but can't confirm now). As with you, I can't change the output colour format or bit depth when plugged into the dock, so it seemed enabling DSC was worse for my case, forcing it back to 30Hz through the dock.

I plugged it back into hdmi, set it to 8-bit through the Intel Command Center and plugged it into the dock again. Now it is defaulting to 8-bit RGB 60Hz through the dock too.

Happy days. I still have to get a DP Cable to I can finally attempt plugging both my monitors into the dock at once (one 4k, the other 1080P)

dcs - thanks for the post 😍

I had resolution issues with a WD19 and Surface Laptop 4 (has 11th gen Intel that does HBR3) only displaying 4K @ 30hz on HDMI and 1080 on DisplayPort.

The DSC registry setting worked for my Surface after a reboot and I now get 4K @ 60hz on HDMI and 4K @ 95hz on the DP!

dcs thank you. I had the same issue with my latitude. The registry setting worked for me!