Custom Resolution Utility (CRU)

[joevt]

Question:

Does CRU work with displays connected to an MST Hub?

I have a Radeon W5700. The Radeon Software Custom Resolutions option is broken because it won't let me choose bpc greater than 6 bpc (plus it only allows up to 10 custom resolutions to be created). So I use CRU to create custom resolutions which work when the display is directly connected to the GPU. But if there is a MST Hub between the display and the GPU, then the custom timings created using CRU do not appear.

Background:

I have three DisplayPort 1.4 MST Hubs:
1) CalDigit SOHO (supports DSC)
2) HP Thunderbolt Dock G2 (updated firmware to support DSC)
3) Delock 87737 (updated firmware to support DSC)

MST hubs that support DSC can accept DSC input and pass it to another device that supports DSC, or decompress it for devices that don't support DSC. Radeon Software gives no indication that DSC is being used. You have to add up the bandwidths to verify that (pixel clock x bits per pixel). Three 4K 60Hz 8bpc RGB is ≈38 Gbps but DisplayPort 1.4 is limited to 25.92 Gbps which means DSC is being used.

My XV273K display has a dual cable mode for 4K 144Hz (it does not support DSC). For single cable connections, it can accept 2.5K 144Hz, 4K 120Hz, 5K 60Hz, 6K 48Hz and 8K 30Hz signals.

Dual cable displays can be connected to an MST Hub. I am able to do 4K 144Hz 8bpc RGB on the XV273K (requires MST DSC input) and 5K 60Hz 8bpc RGB on a Dell UP2715K (MST DSC input not required) but the Radeon Software won't allow choosing 10bpc or higher for some unknown reason (requires MST DSC input in both cases).

Probably Nvidia has better software (no need to use a different app to choose resolution and refresh rate at least) but I haven't verified if it has better MST + DSC support since I don't have an RTX card.

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(03-10-2021 02:37 AM)Aviator_JPN Wrote:  I just purchased the 49" ultra wide by Viotek. (https://viotek.com/viotek-suw49da-49-inc...e-monitor/) It's 5120 x 1440p, 120Hz.
Trying to hook up one desktop and one laptop. And Desktop has both HDMI and DP Connection while the laptop only has HDMI.

When I connect my laptop with HDMI, the laptop recognizes the monitor and shows the resolution of 5120x1440p but the screen is black and says "no signal".

Use a USB-C to DisplayPort cable with the laptop.

(03-10-2021 02:37 AM)Aviator_JPN Wrote:  For desktop, it works fine via DP Connection, but via HDMI, it only works with less resolution and the desktop does not show the resolution of 5120x1440 in the setting.

Lastly the laptop (Dell Inspiron 13, #7373. Bought in 2017) has Intel UHD Graphics 620. And the desktop (Dell XPS 8940, Just bought it) has NVIDIA GeForce GTX 1660 Super 6GB GDDR6.

Maybe the HDMI ports don't support width greater than 4K?
Or maybe the display doesn't support width greater than 4K via HDMI?
Since you know that 5K works via DisplayPort, then you can use a DisplayPort to HDMI adapter that is known to support 5K to test the HDMI inputs of the display. I can get 5120x1440 60Hz 10bpc 4:4:4 to an HDMI 2.0 display using the Club-3D CAC-1080 and CAC-1085.