Limitation of MacPro 2019 with Vega II HDMI and missing 21/9 scaled resolution?

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Limitation of MacPro 2019 with Vega II HDMI and missing 21/9 scaled resolution?

I have a MacPro 2019 with a Vega II graphic card. Everything basically works fine.

However I noticed a limitation of the HDMI port compared with the USB-C ports. I get the same maximum resolution from both port types (so it doesn't seem like a bandwidth issue per se). But, I get less resolution options with the HDMI port.

As luck would have it my optimal (scaled) screen resolution is 3840x1620 (to maintain square pixel width/height 21/9 ratio on My ThinkVision screen 40" 21:9) and it is only available using the USB-C connection to my monitor and not the HDMI.

With HDMI the closest option I get is 3840x2160 which gives a vertically compressed look (where circles becomes ellipses) as it is a 16/9 ratio. All listed HDMI resolutions seems to be 16/9.

I don't know the HDMI vs (Mini Display Port?) USB-C standards enough to know if this is expected but it seems a bit odd to me as the HDMI overall bandwidth seems to support even higher resolutions.

So my question is. Can I get a 21/9 scaling using HDMI or will I be forced to use a USB-C cable?

Cheers!

Mac Pro, macOS 15.4

Posted on May 19, 2025 8:14 AM

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Answer 1

May 19, 2025 11:50 AM in response to aditus162

that Lenovo ThinkVision P40w-20 appear to be a 5120 by 2160 display with 10 bits/color

interfaces include

1x HDMI 2.0 <--- which is inherently limited to 5K at 30 Hz at 10 bits/color or 8 bits/color without compromises

1x DisplayPort 1.4. <--- may be limited to about 60 Hz at 10 bits/color, over THUNDERBOLT

1x ThunderBolt-4 <--- this is the best interface to use

USB-C to DisplayPort cable/adapter does not have the required bandwidth to support this display at high end resolutions. it would likely be limited to 5K at 30 Hz for 10 bits/color, or 8 bits/color.

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MacPro 2019 with Vega II card features:

Four Thunderbolt 3 ports and one HDMI 2.0 port on card
Four DisplayPort connections routed to system to support internal Thunderbolt 3 ports

For this use ThunderBolt-3 and Thunderbolt-4 are plug-compatible. Use a direct cable up to 0.5 meters, or an ACTIVE cable use to several meters.

Once you have full resolution of the display, the built-in scaling provided by the Mac is most likely to produce the best results, rather than manually adjusting the resolution downward.

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The display also has Picture-By-Picture, so could be connected with TWO cables, if desired. This can work with two different interfaces, if needed. Each Left or Right Half-display is set up separately in the Mac, put adjacent with the arrangement pane. In the display, picture-by-picture puts the two halves back together, without any seams or scrolling difficulties. and the required bandwidth on each cable is thereby reduced.

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Answer 2

aditus162 Author

Level 1

12 points

May 19, 2025 11:08 AM in response to Grant Bennet-Alder

The display I use us a Lenovo ThinkVision P40w-20 which is a 21:9 screen.

I have also tried a Displayport <-> USB-C cable and that gives a 21:9 resolution to choose from. The closest I get with this cable i 3360x1417 which is (roughly) 21:9 . But I really prefer some more screen estate which I get with USB-C, i.e 3840x1620.

All cables support the screen maximum resolution of 5120x2160 but the text (for me) becomes too small.

The reason would like to get either HDMI or Displayport to work properly is to be able to be able to use the monitor with both my MacPro and my MacBook without having to physically switch the single USB-C between my MacBok and my stationary to get optimum resolution. (The monitor only have a single USB-C input)

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Answer 3

May 19, 2025 8:28 AM in response to aditus162

what make&model display is this exactly?

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