Displayport 1.2 = no boot

mgmtm3

macrumors member
Original poster
Nov 12, 2016
35
9
Hi everyone,

First let me get the specs out there.
Mac Pro 5.1 (2010)
MacVidCards GTX 1080
LG 38WK95C Monitor

So I'm having an issue with a Mac Pro 5.1 that will not boot at all if I plug in though displayport on 1.2. If I disable displayport 1.2 and then enable it again the computer will get bast the initial boot to the OS and everything works fine. If I leave Displayport 1.2 on it will chime so I know its getting past POST but then nothing else happens. Can't even get the caps lock LED to light up on the keyboard. I have tried multiple different cables as described in another thread about this issue. HDMI also works fine. What could be going wrong here?

Thanks for any help in advance!
 

bookemdano

macrumors 65816
Jul 29, 2011
1,211
701
1080 is Pascal which requires web drivers, right? The MVC EFI ROM on those cards is supposed to not hang at boot on DP1.2 4K monitors AFAIK. My MVC-flashed 750 Ti shows boot screens and boots fine on a 4K DP 1.2 connection, but it's Maxwell.

The Kepler cards, as well as the Radeon 79X0/R9 280 cards definitely do have the hang at boot with DP 1.2 problem.

Have you tried contacting MVC about it?
 

mgmtm3

macrumors member
Original poster
Nov 12, 2016
35
9
I have contacted MVC about it, but thought I'd also get a thread on here as it's close to the holidays so I'm not expecting a quick reply back from them. The card is Pascal and does require the web driver if you want everything to be smooth but even without it will show the boot screens and desktop.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,211
701
Judging from some other users' experiences with them you may not get a reply at all.

By chance do you have two monitors connected? My MVC-flashed 750 Ti will not boot with dual monitors connected. They work fine after booting but it hangs if they're attached during boot. Otherwise though it's always worked fine with a single 4K monitor connected via DP 1.2.

Hopefully someone else with an MVC Pascal card can report on their experience.
 

dgarratt

macrumors member
Jul 16, 2012
42
8
I have a MP5.1 and MVC GTX1080 FE connected to a Dell 4k monitor.

In order to boot or see boot screen I need to disable DP 1.2 in the monitor. I then enable it again once the OS finished loading to get 4k @60Hz.

This behavior doesn't bother me too much as I generally put my cMP to sleep instead of shutting down each day.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,211
701
Ah interesting. So maybe it's just the Maxwell and later cards that don't have that problem.