[Solved] Win 10 doesn't correctly detect 2nd monitor on dual-GPU system?

dwneumann

New Member
I have a system with dual Nvidia GTX 780 Ti GPUs that is set up for dual boot (ubuntu 20.04 & Win10 v21H1 build 19043.1288).When I boot into ubuntu, both monitors are immediately recognized and the desktop extends across both monitors. ... so no hardware or cabling problems. But when I boot into Win10, DeviceManager lists both GPUs but only lists one Generic PnP monitor. Settings/DisplaySettings shows 2 monitors and the "Multiple Displays" setting does appear and is set to "extend these displays". However one of the displays is just listed as "Wired Display" rather than "Generic PnP Monitor" and the desktop does not appear on it. "Identify" does not print the "2" on the 2nd monitor. Both GPUs (the one driving the monitor that works and the one driving the monitor that doesn't) have the same Nvidia driver version 30.0.14.7196 (this is the most recent version that DriverUpdate lists for my system).If I plug the second monitor into another Win10 system (v20H2 build 19042.867) with only one GPU installed, it correctly detects the second monitor and DeviceManager shows two Generic PnP monitors.

So... dual-GPU system works correctly when booted into Ubuntu but not when booted into Win10 v21H1. Same second monitor connected to single-GPU Win10 v20H2 works fine.

Any suggestions? The only thing I can think of is that either I've done something silly or Win10 v21H1 doesn't grok dual GPUs correctly.
 

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dwneumann

New Member
in Nvidia Control Panel, under "Configure SLI, Surround and PhysX", you must select "activate all displays" not "maximize 3D performance".
 
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