converting between video interfaces: HDMI, DVI, DisplayPort
<https://www.barco.com/en/inspiration/news-insights/displayport-to-hdmi-conversion-should-i-use-an-active-or-passive-adapter> This makes it clear where the tricky bits are. For example - what is DP++? - Dual link DVI is "out of scope" for most converters - active vs. passive They don't tell you how to buy the right converter. They don't really explain how HDR signals work. Or "8k" resolution could be supported.
D. Hugh Redelmeier via talk wrote on 2025-05-01 09:21:
<https://www.barco.com/en/inspiration/news-insights/displayport-to-hdmi- conversion-should-i-use-an-active-or-passive-adapter>
This might make a decent companion URL from my bookmarks: https://linustechtips.com/topic/729232-guide-to-display-cables-adapters-v2/?output=DP&input=DVI Lots of info here, often goes over my head. One can choose the type of connectors and then read about the cabling needed. Turns out, I need Active DP to DVI to make best use of my GPU and they're hard to find and / or too expensive these days.
From: Ron via talk <talk@gtalug.org>
The only LTT page I looked at wasn't 100% correct. Single link and dual link DVI have a little more bandwidth. For example 1920 x 1200 @ 60Hz works with single link.
Turns out, I need Active DP to DVI to make best use of my GPU and they're hard to find and / or too expensive these days.
Yeah. I have a couple that I bought second-hand over a decade ago. I take it that you have a dual link DVI port on your monitor. That means that your monitor runs at more than 2000x1200 @ 60 Hz. It also means that it is more than a decade old. I gave up my wonderful monitor with dual link DVE and replaced it with a TV. 40" UltraHD beats 30" 2560 x 1600. Unfortunately, ordinary TVs only do HDMI these days.
D. Hugh Redelmeier wrote on 2025-05-02 16:20:
I take it that you have a dual link DVI port on your monitor. That means that your monitor runs at more than 2000x1200 @ 60 Hz.
No, they're plain full HD 1920×1080. The 1920×1200 uses the DVI output on the same card. So, 1 GPU, 3 monitors: 1920×1200 via DVI, 1920×1080 via HDMI, and ... passive DP->DVI will not run any of them. Hence, a 3rd GPU with DVI. The built-in GPU with DP and HDMI isn't used, since I couldn't get it to work with a discrete one. All this may be partially due to failures on my part, but I did buy a $40 *active* DP->DVI and that did work, but I returned it because $40 for a 3rd monitor wasn't prudent.
On Fri, May 02, 2025 at 04:27:15PM -0700, Ron via talk wrote:
D. Hugh Redelmeier wrote on 2025-05-02 16:20:
I take it that you have a dual link DVI port on your monitor. That means that your monitor runs at more than 2000x1200 @ 60 Hz.
No, they're plain full HD 1920×1080.
The 1920×1200 uses the DVI output on the same card.
So, 1 GPU, 3 monitors: 1920×1200 via DVI, 1920×1080 via HDMI, and ... passive DP->DVI will not run any of them.
Hence, a 3rd GPU with DVI.
The built-in GPU with DP and HDMI isn't used, since I couldn't get it to work with a discrete one.
All this may be partially due to failures on my part, but I did buy a $40 *active* DP->DVI and that did work, but I returned it because $40 for a 3rd monitor wasn't prudent.
Which GPU is this? After all passive adapters only work with DP++ ports not DP ports. Not all GPUs have DP++ ports. -- Len Sorensen
Lennart Sorensen wrote on 2025-05-02 16:58:
Which GPU is this?
After all passive adapters only work with DP++ ports not DP ports. Not all GPUs have DP++ ports.
MSI Radeon RX 570 Armor 8G OC Output: DisplayPort x 3 / HDMI™ / DL-DVI-D DP Ports: 3x DP v1.4 HDMI Ports: 1x HDMI v2.0b DVI Ports: 1 So, I guess no mention of DP++, and since there's already a DVI, no need from their point of view.
On Fri, May 02, 2025 at 05:19:46PM -0700, Ron wrote:
MSI Radeon RX 570 Armor 8G OC
Output: DisplayPort x 3 / HDMI™ / DL-DVI-D
DP Ports: 3x DP v1.4 HDMI Ports: 1x HDMI v2.0b DVI Ports: 1
So, I guess no mention of DP++, and since there's already a DVI, no need from their point of view.
Definitely a google search claims that does not support DP++. It only supports HDMI on the HDMI port. Apparently DP++ became common on newer chips from AMD. Supposedly some cards with the RX4xx had DP++ so it might mean that support for it requires some extra components on the card to detect and switch the mode and some cards didn't bother. -- Len Sorensen
Lennart Sorensen wrote on 2025-05-03 07:40:
Definitely a google search claims that does not support DP++. It only supports HDMI on the HDMI port. Apparently DP++ became common on newer chips from AMD. Supposedly some cards with the RX4xx had DP++ so it might mean that support for it requires some extra components on the card to detect and switch the mode and some cards didn't bother.
Thanks for the info Lennart - now I know *why* I can't do what I want.
From: Ron via talk <talk@gtalug.org>
MSI Radeon RX 570 Armor 8G OC
Output: DisplayPort x 3 / HDMI™ / DL-DVI-D
DP Ports: 3x DP v1.4
Are those DP or Mini DP sockets? For some reason, I found more active Mini DP to HDMI than normal DP to HDMI. Searching on AliExpress is a travesty so my data might be bad. Here's one that might work. $13.58 (free shipping; tax unlikely) "Active Mini DisplayPort MiniDP to DVI Adapter Converter multi-screen Eyefinity adapter cable" <https://www.aliexpress.com/item/32621605064.html> Another theory: maybe there are Apple devices with Mini DP non-DP++ ports. Example:
From a tile that said: DP HDMI compatible | Ultra HD 4k | HDMI compatibe Support: AMD Eyefinity Multi-Dispaly Technology 4K * 2K | Mini DP >>> HDMI-compatible
<https://www.aliexpress.com/item/1005006224629754.html> The "title" is "1.8M Mini DP Display Port Thunderbolt 2 To HDMI-compatible Cable Pro Adapter Plated Gold for Macbook Mini IMac" This is definintely for Mac. It implies that the Mac mini DP port is somehow Thunderbolt 2. It doesn't mention Eyefinity. It seems too cheap to be active.
So, I guess no mention of DP++, and since there's already a DVI, no need from their point of view.
That sounds like the problem. Seems pretty dumb, unfortunate, and surprising.
D. Hugh Redelmeier via talk wrote on 2025-05-05 08:45:
Are those DP or Mini DP sockets? For some reason, I found more active Mini DP to HDMI than normal DP to HDMI.
Full-sized DP ports. Yeah, there are a lot more mini-DP converters out there.
So, I guess no mention of DP++, and since there's already a DVI, no need from their point of view.
That sounds like the problem. Seems pretty dumb, unfortunate, and surprising. I can see the logic behind it, as it likely takes some extra components and anyone who wants to run 3-5 monitors on a single card can probably scrounge up DP supporting monitors.
participants (3)
-
D. Hugh Redelmeier -
Lennart Sorensen -
Ron