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[Dual-GPU] UI Performance Issues w/ Monitor Plugged Into Second GPU

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Recently I have wanted more monitors for productivity purposes so I decided on 6 monitors for my setup. To drive these additional displays, I bought a cheap Gigabyte 1060 6GB card and used my EVGA 780 as secondary for 2 of them.

1060 = 4 displays
780 = 2 displays

Mission Control and other misc. UI elements are perfectly smooth when I only have monitors plugged into my 1060. But as soon as I even have 1 monitor plugged into my 780 alongside my 1060, it causes some pretty severe performance issues; lag, stuttering, delays, etc. Eg. having a single monitor plugged into each (so 2 in total) still causes the lag, even when 4x monitors on either card individually does not cause lag. Lag is also caused when moving windows between monitors across two GPUs.

Really it just comes down to having monitors plugged into both cards is causing lag, but each individual card performs fine. I have the latest Nvidia Web Drivers installed for both Sierra 10.12.6 and High Sierra 10.13, and I experience the lag in both.

I have been unable to find anything on the web detailing this dual-GPU lag, as I imagine it's fairly edge-case. I was holding out that High Sierra would fix this issue, but from what I can tell it has not. I'm also considering switching to Vega for native support, but not entirely sure that would resolve it. Last resort would be to cut down to 4x monitors, buy Vega64 and buy some higher-res monitors to replace the old ones so I at least have similar working area that I did with 6 monitors.

Any ideas?
Thanks!
 
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Well moving windows between monitors MUST technically produce some more overhead. So the lag seems just normal.
But do you have problems keeping the windows on each monitor/card and then working inside the windows? Of course a bad written memory management inside the driver could screw up everything. No idea how good the Nvidia drivers are for MacOS.
But i assume that AMD drivers are better because using two cards is a common Apple setup.

I'm trying to get a 4 monitor setup going with two 7850 (can't get more then 2 monitors running on a 7850) but i have to buy a new mainboard with two 16x pcie slots first.
 
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I'm running dual GTX 760s with the same issues. On my secondary card I get a lot of tearing and other annoying render issues (windows don't refresh so if another window is drawn partially on top the underlying window retains artifacts or simply turns white, or if I drag around a finder window its content is not redrawn and I'm left with bits of the window scattered about on the display).

I'm running the NVidia Web Drivers, on an X58A-UD3R. One card has a PCIe Lane Width of x16, and the other x8. This setup worked flawlessly in Sierra and before using only the Web Drivers and Generic Name.

EDIT: I should note that this system runs 2x 4K monitors via DisplayPort and 2x 1080p via DVI. I only see this issue on the secondary DVI.

EDIT2: The secondary DVI port on the primary card also exhibits this behavior, so I don't think it's card related.
 
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I'm running dual GTX 760s with the same issues. On my secondary card I get a lot of tearing and other annoying render issues (windows don't refresh so if another window is drawn partially on top the underlying window retains artifacts or simply turns white, or if I drag around a finder window its content is not redrawn and I'm left with bits of the window scattered about on the display).

I'm running the NVidia Web Drivers, on an X58A-UD3R. One card has a PCIe Lane Width of x16, and the other x8. This setup worked flawlessly in Sierra and before using only the Web Drivers and Generic Name.

EDIT: I should note that this system runs 2x 4K monitors via DisplayPort and 2x 1080p via DVI. I only see this issue on the secondary DVI.

EDIT2: The secondary DVI port on the primary card also exhibits this behavior, so I don't think it's card related.

Were you able to resolve this?
 
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No, I eventually dropped back down to 1GPU and I can drive two 1080p displays via DVI without issue, but these cards are crazy slow in my High Sierra setup.
 
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No, I eventually dropped back down to 1GPU and I can drive two 1080p displays via DVI without issue, but these cards are crazy slow in my High Sierra setup.

Alright, thanks. Strange the cards are so slow in your setup...
 
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Yeah, I'm not sure why. I've tried running with the default macOS drivers and with the Web Drivers and can see no discernible difference in drawing performance. I plan to bump this card to a 1050 once prices are down a bit more, but this is an old rig anyway.
 
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