MP 1,1-5,1 Triple Display weirdness

[mattspace]

Hey Folks,

Just wondering if anyone else has had issues with their systems going weird on wake / display wake when using 3 displays?

I had twin Benq sw240s (1920x1200), added a third display, an SW270c (2560x1440) and whenever I wake the system, the 240s wake instantly, the 270 takes a few seconds, and the 240s blink on and off with garbled glitches appearing on mostly black screens during the process.

Once all three displays come up, a bunch of windows look like they've been pushed off-centre, to a point roughly between two of the displays, as if one of them is being lost somewhere during the wake process.

GPU has 2x hdmi, & 2x DP. The 240s are on HDMI connections, the 270c on DP.

 

[mode11]

Similar setup to you - 4,1>5,1, 580 Pulse 8GB, 2x 1080p, 1x 1440p, all Dell. I'm using DP for two screens and DVI for the remaining 1080p (with 2x HDMI spare). No issues here. The only minor oddity is that the 1080p connected to DP briefly goes blank after the monitors all come on after sleep, but this is only for about a second, so hardly an issue.

 

[mattspace]

Similar setup to you - 4,1>5,1, 580 Pulse 8GB, 2x 1080p, 1x 1440p, all Dell. I'm using DP for two screens and DVI for the remaining 1080p (with 2x HDMI spare). No issues here. The only minor oddity is that the 1080p connected to DP briefly goes blank after the monitors all come on after sleep, but this is only for about a second, so hardly an issue.

Yeah that DP monitor waking up, then seeming to go back to sleep / black before waking up fully seems to happen here as well. It seems to have settled down after I disabled DDC/CI, and moved the DP monitor to the DP port next to the HDMI ports, and reversed the HDMI screens to the opposite sockets. There seems to be a weird relationship where the physical ports matter to how stable the positioning is when you do virtual arrangement. Rotation seems squirrelly - you rotate a display in the monitors prefpane, and it changes physical position in relation to the other screens as well.

 

[mattspace]

So I just thought I'd post an update on this, now that it seems all solved...

Setup - BenQ sw270c 2460x1440 in the centre, flanked by twin Benq sw240 in landscape orientation. High Sierra and Pulse 580 GPU.

• SW270 is plugged into displayport - it has to be plugged into the DP port next to the HDMI ports.
• Right hand SW240 has to be plugged into the left HDMI port (the one next to the DP connector).
• Left hand SW240 has to be plugged into the rightmost HDMI port - this would possibly make more sense if the Mac Pro's PCI cards weren't upside-down
• You have to arrange the screens AFTER you set the rotation, because changing the rotation moves them in respect to each other.
• The SW270c has to be set to DP 1.1, rather than 1.4 in order to enable recovery mode to display anything - with it set to 1.4, all displays receive signal, but stay black - as soon as you set it to 1.1, recovery mode shows up on the left HDMI screen, un-rotated. Also, the change to 1.1 seems to have stopped the graphical glitching on the HDMI screens when the displays are woken from screen lock / sleep.

The other fun thing I just set up was SwitchResX scaled resolutions for the sw240s - 1390x2226 they're now effectively the same ppi as the sw270, so I can get my span on The small amount of softness the nonnative resolution adds really isn't a big deal.

*edit*

With the SW270c set to DP 1.1, the wake from sleep process would momentarily lose one of the SW240 HDMI displays - the symptom being everything on that display, like app palettes would shift onto the main display, and the Little Snitch connection alert that is generated during wake before I've enabled VPN services would be centred between the remaining two displays.

Switching the SW270c to DP 1.4 seems to have resolved that problem. So the long term solution seems to be DP1.1 for recovery partition, DP 1.4 for general use.