Spectrum won't run 144hz @ 4K | 104 firmware

Hey all!

Having an issue with my Spectrum. I’m running an RX580, which supports DP 1.4. I updated my monitor firmware to 104. It DOES read the link rate at 8.1gbps*4, which is correct for DP 1.4. I just bought a new certified 1.4 cable to make sure. However, my monitor is reporting a refresh rate 60hz max. VRR is 48-60hz. I cannot enable 144hz in Windows unless I switch to 1080p. Custom resolutions do not work above 60hz. Can’t for the life of me figure it out - the monitor is only reporting 60hz at max.

Changing any of the depth or Pixel Format setttings drops the link rate to DP 1.2 levels. Any ideas?

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The RX 580 doesn’t support DSC, so you’ll be more limited on what refresh rates you can hit at 4k while preserving color accuracy. If you really want to hit 4k 144hz, you should be able to by using 8 bit 4:2:2, but you’ll lose color accuracy doing so.

At 4k 10 bit 4:4:4 (or RGB), the max you can reach is roughly 95hz, which is of course a very non-standard refresh rate, so ymmv.

You can do your own fiddling to find your optimal refresh rate/color accuracy with this tool:

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Interesting. I couldn’t find any info on the RX580 and DSC, I looked for that specifically but assumed that it was a part of the DP spec and not to do with the card itself. Thanks!

The issue is I can’t get any refresh rate above 60hz, even by setting custom resolutions. Says the monitor doesn’t support it. If I lower the color depth to 4:2:2, it lowers the link rate of the cable and it doesn’t change anything as to my refresh rate limits, so I’m pretty confused as to these issues.

Edit: before, it would say “not compatible” in Radeon software. Now, it still does that, but for some reason it lets me customize the refresh rate (set to 90hz for now), so a win so far. Going to try CRU. Thanks!

Edit 2: Any custom change to refresh rate locks color space to 8-bit in Radeon. I also can’t change refresh rate much using Custom Resolution Utility unless I set it to Interlaced (ew).

AMD have a page where you can look up information on a good chunk of their CPU range.

https://www.amd.com/en/products/specifications/graphics

Scroll to wayyyy over the right and there’s a column for DisplayPort. You can filter that to only cards supporting 1.4 with DSC and it shows that only the RX 5000 and RX 6000 series have DSC support.

I would have thought that the VESA would have made it a required part of DP1.4, but according to their FAQ page it’s completely optional.

Is DSC designed to be used with DisplayPort or other display interface standards?
[…] It is currently included for optional use in VESA’s Embedded DisplayPort (eDP) Standard v1.4, HDMI and MIPI’s DSI Specification v1.2, and is open for use in other display interface standards as well. […]

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Hi @Walkop, I’ve just got my spectrum yesterday and ran into the same problem like you did with my Vega 56. I’ve tried two different DP 1.4 cables, updated the firmware and set the color depth to 6b, but to no avail. So I wondered, have you found any solution to this in the mean time?

Regarding the GPU’s not supporting DSC, we should still be able to get 4k@120Hz, and even with DP1.2 it should be at least 4k@75Hz.

Perhaps anyone at @Eve is able to shed some light.

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You are in the same boat as us here:

Community Manager responded in that thread saying someone is looking into this issue

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I did come to somewhat of a resolution, using my RX580 without DSC. I can run Spectrum at 4k 8bit 4:4:4 @ 105hz using a custom resolution. Anything higher than that fails.