Mac Pro keeps logging out since El Capitan

That was the first thing I tried. Made no difference at all

The updated driver does not solve the problem: see above.

It appears that the problem is not confined to the NVIDIA GeForce 120 GT card but occurs whenever multiple video cards (of any type) are used to supply multiple monitors.

This seemed to solve my problem, at least it hasn't happened since I installed the update, so fingers Xed!

Thanks a lot

Dave

I had an entire working day without crash by not launching FireFox that I use for playing YouTube vidéo.

Hope a quick fix for this problem.

(3 GT120 cards, 6 screens)

Before I installed the Driver Update, I was using the FireFox too and I can't say for sure if FireFox was always running when the crash occurred. Since installed the update, I've been using FireFox and haven't had any crashes up to now....... Time will tell I for sure I suppose.

I'm using a single (external) monitor without MBA display and I had no problem since closing the MBA display - so that's the workaround.

The problem seems to pop up when using 2 or more displays. I have ONLY 1 integrated GPU, Macbook Air doesn't have dedicated GPU.

Deleted

FWIW, I had a headless Macbook Pro (dead monitor) with this problem after installing El Capitan. I couldn't log in without the windowserver crashing. Solution was to delete all ~/Library/Preferences at the command line via ssh; I tried just deleting the spaces and desktop plist files but that didn't work. So I don't know the specific culprit, other than Apple for shipping a borked OS update.

I have a 2009 Mac Pro with two GT120 cards. I left both cards in but now I am running both displays off one card and that has fixed the issue for now ( so far ). Thanks for all the posts on this issue.

i have had a nightmare with this update too.

It seems this thread is getting a little diluted. I've also not seen any confirmed fixes for the root issue. These are the scenarios that I can see from this thread. If someone else has more information, or wants to add on, please feel free.

Issue:

• Multiple GPU's and Multiple Monitors used in tandem cause the user to be 'force logged out' by means of a kernel panic.
  • The GPU's themselves are not make/model specific.
  • The GPU's have to be in use, as having a second GPU installed and unused does not affect affect anything.
• Multiple monitors on a single GPU does not cause the issue.
• Using a second GPU as a CUDA processor still causes the issue (unconfirmed).
• Isolated issue with Mac Pro 2009 and 2010 models (I have not seen any other reported occurrences in this thread).

Bandaids:

• Turn off "Different Displays have Separate Spaces"
  • Worked for some? - Did not work for me
  • Only delays the logout, but does not fix the issue completely - Reported on this thread
• Only use 1 graphics card
  • While this does fix the issue, it is not ideal for many of us that use graphics intensive programs with multiple monitors
  • Terrible solution for those that use more than two monitors (with caveats for pro/top end cards)
• Install the Nvidia Web Driver
  • Worked for some? - Did not work for me (although did improve performance of my PC GTX 760 while on a single monitor)
  • Problem persists with 2 GPU and 2 Monitors.
• Only use 1 monitor

  Anyone that has used two or more monitors knows...

Same problem here:

Mac pro 2008 8 core 3.0 ghz

1 24 inch cinema display attached via MDP to GT120

1 20 inch Cinema Display attached via DVI to GeForce 8800 GT

It is absolutely reproducible when I launch Lightroom. Before "upgrading" to 10.11 I was using 10.9.5 & had no problems with Lightroom using both displays. You can set up a primary/secondary display in Lightroom, I'm guessing this is what is causing the crash.

Also logs me out at other random times, like when I was trying to fill out a bug report. :-/

Updated drivers & CUDA support, no difference.

Lightroom will launch & no dump out to the login window using only the GT 120. Wish I could use one the 8800 GT but I'd need the MDP adaptor, with is really expensive.

The problem is definitely isolated to using 2 displayed, each on its own video card, for me.

- I have problem with 2009 MP with GT 120 and PC 5770 if one monitor is connected to each card.

- With to to one card no problem.

- With two monitors to one card I can use the GPUs on both cards for calculations without problems

Be careful : I've noticed that after a "back to login screen", TimeMachine don't backup anymore until I relaunch it.