MP 7,1 Problem connecting 3 Radeon Pro W5700X 16GB monitors

[MacBS]

Hello everyone,
I just bought an AMD Radeon Pro W5700X 16GB graphics card on eBay for my 2019 Mac Pro 7.1.
The problem is that this card is supposed to support 6 screens,

(I have three 27-inch Iiyama monitors (ref: Prolite B2783QSU)).
So where's the problem with connecting three?

My setup with this card is as follows:
1st screen connected to the card's HDMI port, which works.
2nd screen connected to a Bus 0 port (with a USB-C adapter).
3rd screen connected to a Bus 1 port (with a USB-C adapter).
Of the three connected screens, only the one connected via HDMI works.
The other two remain black.

I tried connecting the USB-C cables to the top of the Mac Pro, as well as to the top rear panel.
I also tried the other two screens, which are only recognized via HDMI.
The refresh rate on HDMI remains the same. (Maximum 60 Hz)
For the next two, I can adjust them (maximum 69.88 Hz), which
I did, but without success.

Could someone help me or explain why?

Sincerely.

 

[Bigwaff]

Do the displays appear in System Information app under Displays or either the Thunderbolt buses?

 

[reader50]

Which USB-C adapter are you using? Not all USB-C devices are created equal.

 

[MacBS]

Which USB-C adapter are you using? Not all USB-C devices are created equal.

Here are the cables used for the MPX W5700
For the 3 screens:

1 HDMI to DVI 4K cable
1 DisplayPort cable + USB-C adapter
1 DisplayPort cable + USB-C adapter

Attached are photos of the two adapters.

Best regards.

 

[choreo]

I purchased a 2019 Mac Pro new in July 2020 with a W5700X card pre-installed. I have always had (3) 27" monitors connected since the beginning (no problems). In the beginning I had (3) NEC QHD monitors and I ordered (3) DisplayPort x USB-C cables from Monoprice to connect them (no adapters). The past couple years I switched out all three NECs for new 27" 5K ASD's (using their included USB-C x USB-C cables) - no problems still. I have never used the HDMI port, only three of the four USB-C ports on the W5700X card. My first "guess" would be the adapters - I had some problems when first setting up until I ordered the right dedicated cables.

 

[reader50]

Could you give us a link to the adapter you are using, on Amazon or wherever you got them? That's what I was asking for, so we could check the specs. And the reviews, like if other Mac users reported problems with them.

For example, your adapter might be for DisplayPort to a USB-C monitor input. The opposite of what you're using them for. Not all adapters are reversible.

 

[MacBS]

I purchased a 2019 Mac Pro new in July 2020 with a W5700X card pre-installed. I have always had (3) 27" monitors connected since the beginning (no problems). In the beginning I had (3) NEC QHD monitors and I ordered (3) DisplayPort x USB-C cables from Monoprice to connect them (no adapters). The past couple years I switched out all three NECs for new 27" 5K ASD's (using their included USB-C x USB-C cables) - no problems still. I have never used the HDMI port, only three of the four USB-C ports on the W5700X card. My first "guess" would be the adapters - I had some problems when first setting up until I ordered the right dedicated cables.

Indeed, I think you're right. I just ordered three 2-meter DisplayPort to USB-C cables from Amazon. I'll connect them to the back of the card following your helpful advice.
(As an aside, I sent several messages with photos to the seller on eBay asking if they could explain how to connect three monitors to the MPX W5700. Each response was completely irrelevant to my question, so the sellers were clearly incompetent.)
However, on my MPX 580 8GB, I'm connected with one 4K DVI to HDMI cable, and the other two are DisplayPort + USB-C adapters, in case anyone is interested.
Thank you very much for your reply.

 

[MacBS]

Could you give us a link to the adapter you are using, on Amazon or wherever you got them? That's what I was asking for, so we could check the specs. And the reviews, like if other Mac users reported problems with them.

For example, your adapter might be for DisplayPort to a USB-C monitor input. The opposite of what you're using them for. Not all adapters are reversible.

Here are the links for the two adapters on Amazon:

Hama Adaptateur USB-C vers HDMI 4K Garantie 10 Ans (Adaptateur Thunderbolt 3/4 USB-C vers HDMI, Compatible iPhone15, MacBook, iPad, iMac) Noir

www.amazon.fr

For the first screen, use a DVI to HDMI cable connected to the back of the card.
For the next two screens, use a DisplayPort adapter connected to a USB-C port. No problem with the MPX 580 GB.

For the MPX W5700 16 GB, only one screen will work with a DVI to HDMI cable connected to the back of the card.

The next two screens do not work with DisplayPort adapters, regardless of the USB-C port.

 

[reader50]

The linked adapter is USB-C to HDMI, so presumably you're using the HDMI inputs on the two problem screens.

This adapter seems like a low-end one. Lots of user complaints in the reviews of it not working. Also, it's limited to 30Hz at 4K, presumably with 8-bit color per pixel. Your monitors are 2560x1440 (at 60Hz?) so they'll be near the bandwidth limit for this adapter.

I suggest a different adapter. Preferably one that converts to DisplayPort, and is rated for 4K at 60Hz minimum. That gives you a safety margin, and you'd be good for your next monitor upgrade. Your monitors have both HDMI and DisplayPort (and DVI) inputs. You'll generally find connection via DisplayPort to be more stable in my experience.

 

[MacBS]

The linked adapter is USB-C to HDMI, so presumably you're using the HDMI inputs on the two problem screens.

This adapter seems like a low-end one. Lots of user complaints in the reviews of it not working. Also, it's limited to 30Hz at 4K, presumably with 8-bit color per pixel. Your monitors are 2560x1440 (at 60Hz?) so they'll be near the bandwidth limit for this adapter.

I suggest a different adapter. Preferably one that converts to DisplayPort, and is rated for 4K at 60Hz minimum. That gives you a safety margin, and you'd be good for your next monitor upgrade. Your monitors have both HDMI and DisplayPort (and DVI) inputs. You'll generally find connection via DisplayPort to be more stable in my experience.

Thank you,
your answer concerns the MPX 580 8GB.
Here is my setup for the 580
For the 3 screens:
1 HDMI to DVI 4K cable
1 DisplayPort cable + USB-C adapter
1 DisplayPort cable + USB-C adapter
For this card, the HAMA adapters work
perfectly. They do not work for
the MPX W5700.

What I wanted to tell you was mainly about
an MPX W5700X card with a setup for 3 screens.

For the MPX W5700 16GB - only 1 screen will work
with 1 DVI to HDMI cable connected to the back of the card.

The other 2 will not be recognized with DisplayPort + adapter
on any USB-C port on the top or back of the MP.

You'll need to connect three DisplayPort to USB-C cables (without an adapter): one cable to the top of the Mac Pro, and the other two to the W5700X motherboard.
Yes, DisplayPort is indeed more stable.

Sincerely

 

[reader50]

Both those cards are native Mac cards. I wonder if the 580 is defaulting to 8-bit color per pixel, while the 5700 is defaulting to 10-bit. Pushing the adapter beyond its bandwidth limit.

A conversion cable (or higher-grade adapter) are the likely fixes.

In the meantime, doesn't your MPX W5700X have two HDMI output ports? Seems like you could at least get two monitors working with HDMI cables, while you sort out the adapter problem.

 

[mattspace]

Thank you,
your answer concerns the MPX 580 8GB.
Here is my setup for the 580
For the 3 screens:
1 HDMI to DVI 4K cable
1 DisplayPort cable + USB-C adapter
1 DisplayPort cable + USB-C adapter
For this card, the HAMA adapters work
perfectly. They do not work for
the MPX W5700.

What I wanted to tell you was mainly about
an MPX W5700X card with a setup for 3 screens.

For the MPX W5700 16GB - only 1 screen will work
with 1 DVI to HDMI cable connected to the back of the card.

The other 2 will not be recognized with DisplayPort + adapter
on any USB-C port on the top or back of the MP.

You'll need to connect three DisplayPort to USB-C cables (without an adapter): one cable to the top of the Mac Pro, and the other two to the W5700X motherboard.
Yes, DisplayPort is indeed more stable.

Sincerely

The HDMI port is bus 0 and always gets first enumeration at boot, try not using it at all. I have my 3 screens on my first W5700X in TB1, TB3, and TB4. If I want to plug in a recently acquired 50" TV, I use the HDMI port on my second W5700X in slot 3, which gets enumerated after the ports in slot 1, to prevent the display arrangement getting messed up by competition for the "proper" menubar screen.

Go back to first principles, try each screen with a direct cable, rather than adapters, that rules out the adapters. Try each screen in each port, rule out individual ports being broken. Use three identical Type-C to Displayport cables.

Also worth considering whether the reason it's not displaying properly is that the firmware have been messed with, but there are other people here better qualified to talk you through that.