Monitor Input issue

[PitBullCH]

Greetings,

I have a MacPro 3.1 (Early 2008) with 64GB RAM, 2x 3.2GB Quad Xeon CPUs, and an EVGA nVidia 680 Mac Edition GPU - O/S is fully patched to latest Yosemite.

The GPU has DP, HDMI and DVI-D outputs, and historically this was connected via DVI-D to an old (circa 2008) BenQ 1920x1080 monitor - worked well enough but recently the itch started for a 4K monitor...

So I bought an LG 31MU97 monitor - this has DP, miniDP and 2x HDMI inputs, and currently I am using it at 4096x2160x50Hz using DP-DP connection.

This works fine most of the time - and after i1Profiler calibration it's actually a very nice display (although the monitor controls via the little joystick suck and the OSD is painfully slow).

However when I boot the system it never sees the DP connection and won't boot - I have to connect an HDMI cable and switch to HDMI input to have it boot and then I can switch back to DP - although sometimes it still doesn't see DP and I then have to faff around with multiple displays in the Displays Sys Prefs and then disconnect the HDMI. Very irritating.

Same issue with DP-miniDP.

Any thoughts on what to try to resolve this ?

Regards.

PitBull (in Switzerland)

 

[mikeboss]

AFAIR this behavior is specific to the MacPro3,1 (not booting with GTX 680 and 4K display). MacPro4,1 and 5,1 will boot but you won't get bootscreens.

EDIT:
yep, found my post from last year about this issue:
https://forums.macrumors.com/posts/19184842/

 

[PitBullCH]

Hi Mike - thanks for that response.

Do you know if this is also an issue with other cards or just the 680 ? I was hoping to get a Titan X from MacVidCards (when they get some stock in)...

 

[nigelbb]

Does it boot OK if you have a second monitor connected to one of the HDMI ports?

 

[mikeboss]

Do you know if this is also an issue with other cards or just the 680 ?

I don't know. I returned the 4K display after fiddling with it for a few days...

 

[PitBullCH]

It boots fine with just HDMI, or with HDMI and DP to the same monitor (haven't tried with 2 monitors).

 

[ilandmac]

It boots fine with just HDMI, or with HDMI and DP to the same monitor (haven't tried with 2 monitors).

I have sort of the same issue.

Running a MacPro early 2008 flashed, with Radeon HD7950. Mavericks 10.9.5

Booting with both Apple Led display & 31MU97 connected to display port boots to the Apple screen.

The only way that I can boot with the LG screen alone is to add an HDMI connection. It will boot on that then I have to select the display port from
the LG menu. The screen will come up greyed out with nothing on the desktop.

Unplugging the HDMI connector brings things back to normal.

The thing is, once you've tasted the display port's 60 hertz there's no going back to the 30 hertz of HDMI...

Tedious.

 

[PitBullCH]

Hi Mike - thanks for that response.

Do you know if this is also an issue with other cards or just the 680 ? I was hoping to get a Titan X from MacVidCards (when they get some stock in)...

Just as an update - I never did get the EVGA 680 to boot with just a DP cable - so had to leave HDMI cable connected.

I've since replaced it with a Titan X from MacVidCards - happy to say that this boots up normally with a DP cable (or HDMI) and works fine.