Installed El Capitan in system (in signature) with two GTX Titan Black GPUs. GPUs not supported natively (Found this odd, as all Keplers are apparently supported natively as of 10.9) Booted with nv_disable=1, installed Nvidia web drivers 346.03.03f02 after installing El Capitan 10.11.1.
Rebooted and got black screen after loading. After a couple minutes, the cursor appears. I moved it around to find the password input box (Completely invisible, but cursor changed to text input icon) and then typed my password, after which I get the spinning beach ball loading icon and nothing more. Tried booting with only one GPU installed, same issue.
Managed to properly boot into OS with nv_disable=1. (Albeit, at a low 1024x768 resolution with various visual glitches) Not sure why the drivers don't work, searched around and no one seems to have this issue except with Maxwell cards, and the fixes I've found don't work.
So, I tried an old AMD card I had on hand to replace one of the Titans.
The system booted fine, with the AMD card being seen as a generic card (Working very much like the Titan with "nv_disable=1"). Oddly, the monitor hooked up to the remaining Titan worked as it should with the proper resolution. System profiler shows the Titan as it should, with all the proper specifications.
I put the other Titan back into place and the issue occurs once again. Tried with only the one that worked before (In the same secondary slot) and I got nothing, something about having the AMD card installed changed its boot behavior.
Booted with the AMD card again, the display hooked up to the Titan no longer showed any display. System Profiler still showed it as hooked up though, so I reconnected it. This caused the monitor to turn on and display as it should, but the entire system froze a few seconds after. After a few minutes, I was given a login prompt again, and after logging in, everything works as it did the first time I had the AMD card connected.
Tried to open Safari, it lags a lot, freezing up the system each time it does for 30 - 60 seconds, though I think it may have something to do with the AMD card being the primary card (And only having 5MB VRAM accessible). It would seem acceleration does not work properly with this configuration.
Boot Arguments: (Clover)
"dart=0 kext-dev-mode=1 nvda_drv=1"
Any help is appreciated.