RX580 Mojave Triple Monitor Issues

simplymuzik3

macrumors 6502a
Original poster
Jan 29, 2009
589
0
Hey guys,

Running a stock (non flashed) Sapphire RX580 with 3 x 27" Apple Cinema Displays. Have never had issues before Mojave. Now, only the 2 monitors connected via DisplayPort show up. I've previously used adapters for the 3rd one (either connect via dual link DVI or HDMI) and it has never caused issues.

No matter what I try, I can't get my 3rd monitor to show up. I've tried every combination of adapters and only the 2 DisplayPort ports seem to work. Anyone else have this issue or possible solution? Used the search function but couldn't find anything.

I just updated to the latest Mojave release from yesterday in hopes it would fix itself. No luck. The 3rd monitor doesn't even show up in system report. The screen does a slightly black/dark grey transition for a split second as if it's going to connect/turn on, but then it goes back to staying off and the computer doesn't detect it in any way.

Thanks!
 

h9826790

macrumors G5
Apr 3, 2014
12,990
5,867
Hong Kong
Hey guys,

Running a stock (non flashed) Sapphire RX580 with 3 x 27" Apple Cinema Displays. Have never had issues before Mojave. Now, only the 2 monitors connected via DisplayPort show up. I've previously used adapters for the 3rd one (either connect via dual link DVI or HDMI) and it has never caused issues.

No matter what I try, I can't get my 3rd monitor to show up. I've tried every combination of adapters and only the 2 DisplayPort ports seem to work. Anyone else have this issue or possible solution? Used the search function but couldn't find anything.

I just updated to the latest Mojave release from yesterday in hopes it would fix itself. No luck. The 3rd monitor doesn't even show up in system report. The screen does a slightly black/dark grey transition for a split second as if it's going to connect/turn on, but then it goes back to staying off and the computer doesn't detect it in any way.

Thanks!
27" ACD via HDMI / DVI port?
 

simplymuzik3

macrumors 6502a
Original poster
Jan 29, 2009
589
0
Will take a look. Thanks!
[doublepost=1553614055][/doublepost]
27" ACD via HDMI / DVI port?
Yeah, I've got a Mini DP > dual link dvi adapter box (Atlona DP400). It's been working great for the last 7 years across all Mac OS versions until now.

I thought it was the adapter so I got an HDMI solution: Mini DP to regular DP adapter (passive). Then DP > HDMI (active).
 

h9826790

macrumors G5
Apr 3, 2014
12,990
5,867
Hong Kong
Will take a look. Thanks!
[doublepost=1553614055][/doublepost]

Yeah, I've got a Mini DP > dual link dvi adapter box (Atlona DP400). It's been working great for the last 7 years across all Mac OS versions until now.

I thought it was the adapter so I got an HDMI solution: Mini DP to regular DP adapter (passive). Then DP > HDMI (active).
I think DP > HDMI active adaptor is single direction, which is for DP (output from the graphic card) to HDMI (monitor). In your case, it's HDMI to DP.
[doublepost=1553614834][/doublepost]Are you using the PULSE RX580 8GB card?
[doublepost=1553614915][/doublepost]Did you run that RX580 with High Sierra before?
 

skizzo

macrumors regular
Apr 11, 2018
238
68
I think DP > HDMI active adaptor is single direction, which is for DP (output from the graphic card) to HDMI (monitor). In your case, it's HDMI to DP.
[doublepost=1553614834][/doublepost]Are you using the PULSE RX580 8GB card?
[doublepost=1553614915][/doublepost]Did you run that RX580 with High Sierra before?
good catch on the single direction cable. I've never seen a cable that takes a HDMI output to a DP/mDP input. I bought a DP --> HDMI cable a few years ago and recall my research suggesting it is always going from DP/mDP out to HDMI input, it cannot work the other way around

quick amazon search brought up converter ive never seen before though. check this out
https://www.amazon.com/DisplayPort-Converter-FOINNEX-Adapter-Powered/dp/B07G796JF8/ref=sr_1_14?crid=10MT7LVEY5IZJ&keywords=hdmi+to+displayport+cable&qid=1553625586&s=gateway&sprefix=HDMI+to+di,aps,149&sr=8-14

could be a solution for the OP if they use a DP to mDP cable from this adapter.

so it would be: RX580 HDMI --> HDMI to DP converter --> DP to mDP cable --> ACD

still though, seems funny why the DVI to mDP adapter doesn't do the trick if it worked under earlier macOS versions.
 

simplymuzik3

macrumors 6502a
Original poster
Jan 29, 2009
589
0
I think DP > HDMI active adaptor is single direction, which is for DP (output from the graphic card) to HDMI (monitor). In your case, it's HDMI to DP.
[doublepost=1553614834][/doublepost]Are you using the PULSE RX580 8GB card?
[doublepost=1553614915][/doublepost]Did you run that RX580 with High Sierra before?
You might be right about the cable. Just trying to make it work with the Mini DP > Dual Link DVI for now since I know that works. Yes was using it in High Sierra and all previous Mac OS versions since the 27" Cinema Display came out like 10 years ago.
[doublepost=1553640258][/doublepost]
good catch on the single direction cable. I've never seen a cable that takes a HDMI output to a DP/mDP input. I bought a DP --> HDMI cable a few years ago and recall my research suggesting it is always going from DP/mDP out to HDMI input, it cannot work the other way around

quick amazon search brought up converter ive never seen before though. check this out
https://www.amazon.com/DisplayPort-Converter-FOINNEX-Adapter-Powered/dp/B07G796JF8/ref=sr_1_14?crid=10MT7LVEY5IZJ&keywords=hdmi+to+displayport+cable&qid=1553625586&s=gateway&sprefix=HDMI+to+di,aps,149&sr=8-14

could be a solution for the OP if they use a DP to mDP cable from this adapter.

so it would be: RX580 HDMI --> HDMI to DP converter --> DP to mDP cable --> ACD

still though, seems funny why the DVI to mDP adapter doesn't do the trick if it worked under earlier macOS versions.
That's the kind of adapter I have. Was around $80 CAD. Just trying to make it work with my Mini DP > Dual Link DVI for now since that's what previously worked in all older Mac OS versions. Thanks for the help!
 

MevetS

macrumors newbie
Dec 27, 2018
29
11
Earth
Not exactly the same issue, but similar. I have the Sapphire Pulse RX580 with two monitors, 20" Cinema Display and 23" Cinema HD display. The other day I came home to find the 20" while powered on, showed only a blank screen and it was not identified as connected to the system (under "About this Mac" > "Displays" it did not show).

Short story: I shut the system down, unplugged the display from the power strip, waited a bit, plugged it back in, and restarted. And the monitor resumed working. And has been since.

Note that I had already upgraded to Mojave and my set up had been working fine.

And I assume that you have swapped monitors to confirm that all three still work. Correct?

Longer story: At first I thought one of our cats had gotten behind the system and pulled a cord out. So I reseated the connections. Didn't fix it. Then I swapped ports, to see it there was a port problem. Nope, the same monitor worked. Maybe the adaptor was bad, so I swapped them. Nope. I was then going to hook the display up to another system to make sure it still worked, and I don't know why I decided to unplug it and plug it in again. Glad I did.

Good luck.
 
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