[A12 & A13] Performance problems with mixed-GPU multimonitor

[ro.othorick]

I think this is a bug with Unity in general, but bears mentioning here. I've ONLY observed it with Unity games; some kind of timing issue that prevents the framebuffer from being transferred to the "slave" GPU at a reasonable speed maybe?

In any case, in fullscreen, or if the window crosses/gets close to the boundary between monitors, framerate gets stuck around 30fps or lower. Even on the main menu. And there's a noticeable stutter.

I'm running a GTX 760 as my main screen, and my secondary monitor, above the primary, is run by my Intel ondie.

I've just been running the game windowed as a workaround for the time being.

[milon]

Interesting.  I have a dual-display setup running Win7 x64 Pro.  My primary display runs off the onboard video and the secondary runs off the video card (an older ATI Radeon something-or-other).

Whenever I ran RimWorld (fullscreen - I don't recall if I tested windowed mode), the computer would always crash within 30-60sec.  According to the Windows log, it shut down due to overheating of the external graphics card, even though RimWorld was only on the primary display.  I assumed it was just my computer being old and crappy.

My solution was to write a 3-line script that first disables the 2nd display, then runs RimWorld, and then re-enables the 2nd display after RimWorld exits.

It sounds like something is getting badly overworked when there's more than 1 display present.  Has anyone else experienced this with RimWorld or other Unity apps?

[Bancheis]

I would probably first check the Nvidia control panel "Manage 3D settings" options and check the Global Settings tab for "Multi-display/mixed-GPU acceleration" and ensure it is set to "Multiple display performance mode". Also above that, make sure the Maximum pre-rendered frames option is set to use the 3D application settings.

If you have not already done so, I would also recommend checking if you have a graphics driver update that can be installed.

[1000101]

My desktop runs a three monitor setup off two discrete video cards (2GB Zotac 950GTX 16xPCI-E v3, 1GB Zotac 450GTS 4xPCI-E v3) and haven't noticed any issue, but have only run the game in fullscreen on the primary (950GTX) display.

You may need to check for updated drivers (I only have to run one driver set for both cards, thankfully) for your motherboard and both the onboard and discrete video.  I don't know how well Unity4 plays with video cards from different vendors in the same class (ie, two NVidia xy0 cards from different vendors) or different hardware manufacturers (ATI+Intel/ATI+NVidia/NVidia+Intel/etc).  It wouldn't surprise me if it was your motherboard or OS which is causing the issue.  Some motherboards don't work well using the onboard with a discrete video card and Windows itself sometimes has issues running multi-monitor configurations with different manufacturers.

More details about your system would help (Motherboard, OS, driver versions) to diagnose the problem.

[Tynan]

You're probably right, but this would be 100% a Unity issue. I've really got no access to video code, so I have to close this. Sorry.