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PC Graphics

Skuldwyrm
Journeyman III
Thursday

DisplayPort™ 2.1 – Full UHBR20 support 9070XT (RDNA4) ?

I can't find info, or tests about the ned 9070 and 9070XT cards and what they support.
Per wikipedia UHBR20 is available from Displayport 2.1 onwards.

The 7900 XTX had UHB13.5 (54Gbps).
Sadly it can't deliver uncompressed 4K 240Hz 10bit to my OLED (which has Displayport 2.1 UHBR20).

9070 XT seems like a good buy on it's own, but if AMD still only has UHB13.5, the new card would be a downgrade in memory (from 24GB to 16GB) and a slight downgrade in raster performance.
The improved Raytracing and AI stuff is nice, but not enough to replace my 7900 XTX.

But... if the 9070XT has UHBR20 then I might be tempted to get it (and put the 7090 XTX into a older box for AI/LLM/rending/etc. stuff).

There is one website and one video that list UHBR13.5 but I have no clue where they got their info, I doubt they actually tested it with a UHBR20 display.

And there is no info on AMD's pages, nor on card manufacturer pages.

 

 

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3 Replies
fsadough
Moderator
Moderator
Friday

UHBR20 is tied to DP 2.1 specification and not to the GPU. Radeon RX 9070 supports DisplayPort 2.1

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Skuldwyrm
In response to fsadough
Journeyman III
Friday

So you are saying the 9070 and the 9070 XTX can do UHBR20 / 80Gbps ?

I don't think you understood my question.

Because I do not want to buy the new card, boot up and in the AMD driver software see it say "Current Link Settings 13.5 Gbps x 4" (which is UHBR13.5 / 54Gbps)

when it's supposed to say "Current Link Settings  20 Gbps x 4" (which is UHBR20 / 80Gbps)
And then have to return my card, and drum my fingers and wait for the major competing brand to be available, because they are actually listed with specs saying they support UHBR20.

Currently with the 7900 XTX i have to use CRU to tweak the EDID timings for 240Hz 4K at 8bit, which makes the card happy and allow UHBR13.5.
Without tweaking with CRU the card drops to UHBR10 with DSC (Display Stream Compression) enabled.
This is due to the bandwidth limit of the Pixel Clock on the card (which drives the Displayport output).

If the 9070 XTX truly can do UHBR20, then I would be able to do 240Hz 4K at 8bit or even 10bit without having to mess with CRU, and without DSC enabled.

I do a lot of productivity stuff so Id'a rather not have DSC active, also if gaming, and taking advantage of of the new RDNA upscaling and framegen there is enough "noise/artifacts" that I don't want to layer DSC on top of that.
  

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fsadough
Moderator
Moderator
12 hours ago

Your concern is kinda related to the marketing strategy between AMD and competitor. I explained to you in my previous comment that UHBR is a DisplayPort spec by VESA standards and not GPU/ASIC related. When we specify that Radeon RX 9070 supports DP 2.1 then it means we follow the specs of VESA.

 

If AMD driver software says "Current Link Settings 13.5 Gbps x 4" (which is UHBR13.5 / 54Gbps), this could have other root causes, like a bad cable/adapter (DP80 Cable required for UHBR20) or corrupt EDID by the monitor.

 

All Radeon RX 9070 series are made by AIB partners like ASUS, Gigabyte, MSI and so on and we have no influence on how they market the product.

  1. DP 2.x supports DSC & UHBR20
  2. 4K@240Hz 10bpc requires 68.56 Gbits/s and hence supported by UHBR20=77.37 Gbits/s
  3. UHBR20 is supported by DP 2.1 as per VESA standards

Please contact the AIB partner of your choice if you specifically need their confirmation on UHBR20 support by Radeon RX 9070 series 

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