Will Not Boot with New Display Monitors!!??

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15 points

Will Not Boot with New Display Monitors!!??

Hello--I'm running a MacPro 5,1 with an AMD Radeon HD 7970 3072 MB GPU. Up until last week I was running 2 x Apple 27" Cinema Displays. I decided to get slightly larger, slightly better monitors so I bought two Dell S3221QS monitors. The Dell is connected with a single cable, 4K certified mini DP on the GPU end and DP on the monitor end.

Rather than connect all new all at once, I did one monitor at a time, removing one Apple Cinema Display and replacing with one of the Dells. All was great and I ran that way since last week.

Today I decided to remove the second Apple Cinema Display and replace with the second Dell S3221QS. When I briefly did that, and ran for a little while, all was well. I then tried to bring up the Calendar app from my dock, and Calendar wouldn't start. So, I restarted the system.

It would NOT restart with the two Dells. At all. No input to the monitor (OSD on monitor says no signal from DP). I tried several times, same thing. If I remove ONE of the Dells, I will get at least a white screen (but no Apple) but still no boot.

So, I connected the Cinema Display back up, and that works just fine. I shut down, and added back ONE of the Dell monitors, and voila--that works well too!

So, why isn't the system booting with both Dells? Why isn't it booting with one Dell? But why can I use the Dell as a secondary monitor?

Help please!

Mac Pro, macOS 10.14

Posted on Mar 9, 2021 9:37 AM

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Answer 1

mdsalemi Author

Level 1

15 points

Mar 11, 2021 7:19 AM in response to mdsalemi

OK, I have a work-around, but not satisfied with the setup...hoping that things may be different when I upgrade to a 2018 MacMini.

Using DP cables from the card to the monitor, the system will NOT boot up. Doesn't matter if there is one or two monitors connected. Dell Monitor + DP cable? NO BOOT.
Using HDMI cable from card to monitor (single monitor), the system WILL boot up, and will run at pretty much any resolution for a single monitor--including 4K. Nice if you run a single monitor. I've been on two for a decade.
Adding the second monitor to 2) above, I can use a DP cable...but ONLY after the system is booted up! At high res/4K, one of the monitors is at 30Hz and the second is at 60Hz. When the second monitor is connected, it will NOT reboot. See 1).
Setting both 4K monitors to 2160x1440 (which was the Cinema Display resolution), one of them is at 60Hz, the other at--get this--59.88 Hz. Seriously? Seriously! Funny when two Cinema Displays were connected, they ran at 60Hz, but both of those were through the DP cables, not the HDMI.
No sound. From the best that I can tell, sound for these monitors comes through either the DP cable, or the HDMI cable; there does not seem to be an AUDIO IN separately. However, Apple in their infinite wisdom ONLY sends sound out the DP cable IF the monitor detected is an Apple monitor. If the monitor is not Apple, the sound out choices are limited to: Internal Speaker (internal to the MacPro, which is crap); Line Out (audio line out) and Digital Out. So, no way to get sound from the MacPro to the monitor.

Maddening. Very, very maddening.

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Answer 2

mdsalemi Author

Level 1

15 points

Mar 9, 2021 12:17 PM in response to Johnb-one

Thanks guys..don't know if I've been helped yet. Yes, the GPU is "Mac Flashed" and in fact, was always a Mac AMD Radeon HD 7970 3072 MB; in other words, not some PC or gamer version hacked to a Mac by bios flashing or what have you. Been installed for years in the MacPro. No issues.

No adapters; only a single MiniDP on Mac end, and DP on Dell end. Both the same. No interface mixing.

Well, you know--Apple CEASED making monitors a long, long time ago. they do make MacPros beyond my 5,1. The 6,1 ran from 2013-2020, and now they have the 7,1. So, they have to be able to support monitor standards.

Dell support is useless. No human beings, mostly, and if you get one, they don't speak English and really don't know anything about the hardware. Like, at all.

Apple support isn't relevant to me, as this system is way beyond their support window.

I'm running High Sierra.

As you can see from the screen shot, when I'm running ONE Cinema Display and ONE Dell, the Dell is recognized and all is well. I have it clicked to SCALE DISPLAY only to illustrate the resolution the display is operating at.

The fact that each of the Dells works in this manner, and so do the Mini-DP to DP cables, tells me that the monitors are OK and the cables are OK. Just cannot get the system to boot with both connected.

I THINK the AMD Radeon HD 7970 is capable of running two monitors out of the two Mini DPs at the Dell resolution, but I'm not certain. It certainly worked for years with the two Cinema displays...which are of course, lower resolution.

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Answer 3

Mar 9, 2021 10:24 AM in response to mdsalemi

I presume, since you did not say differently, that you are using similar Mini DisplayPort to DisplayPort on the monitor end. If you are using HDMI, everything is different.

... and that you are making the conversion from computer output port to display input port in at most ONE cable/adapter. "stacking" adapters is perilous, and does not usually produce anything.

... and that you connected the computer-end of the cable LAST, and tried to sleep and wake your Mac afterward to get it to recognize the displays. [command-Option-Power or Command-Option-Eject to sleep, momentary power button or keyboard key to wake.]

Do you have another Mac. that you could use to "screen-share" in and read out

 menu > about this Mac > (system report) Graphics & Displays ... ??

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Answer 4

Johnb-one

Level 6

9,180 points

Mar 9, 2021 10:20 AM in response to mdsalemi

I can help you somewhat, mdsalemi. It’s been my experience that Dell monitors may work, but they do not play nicely with Macs, any Macs at all. Don’t talk to Dell about it, they’ll tell you they don’t support Macs-PC only.. and they’ll tell you to talk to Apple, and Apple wil tell you it’s a PC monitor which is techncally true.. nowhere on the Dell website for this monitor does it mention Mac support.. basically the Mac talks to the Dell Monitor and it Has to send the signal back to the Mac to identify itself that the Mac can Recognize, this is something the Dell Monitor doesn’t really do. I used to have a Dell monitor and the only way for me to get it to work was to unplug and replug the power cable going to the monitor. Sometimes, I would have no trouble with it and sometimes I would, And sometimes it would decide to give me trouble and go peculiar on me after a while. It was never really consistent or predictable. here’s what I did to solve that problem: link

https://gist.github.com/ejdyksen/8302862

please note that with catalina etc, you will have to reboot from the recovery partition and temporarily disable system integrity protection( sip)

i do not know what version of the Mac OS you have/are running, only that you have 2 Dell monitors and a Mac Pro 5,1, with an AMD Radeon 7970 card, which i assume has been Mac flashed and that the switch on that card, if there is one, is in the correct position...

john b

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Answer 5

Mar 9, 2021 10:35 AM in response to Johnb-one

this is my "canned" speech on the subject of identifying displays:

to get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• on invoking Option-(Detect Display) button in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

Modern Displays with multiple ports are sometimes busy scanning the other ports, looking for an input, and miss the query from the Mac. They need to pay attention to the port you are actually using, or they will miss the query.

Some displays have On-Screen Display settings that can be used to tell the display a computer is attached on a certain port, or a certain port should be highest priority. Changing those may make your display more responsive.

Some displays include their own private "sleep" settings for the display alone. This can allow the display to enter its own sleep mode, on top of the Mac's not sending it data. A display that is sleeping on its own cannot respond to the Mac's query, and will stay dark.

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Answer 6

Mar 9, 2021 12:57 PM in response to mdsalemi

You increase resolution for BOTH? Perhaps you have exceeded the total resolution for the display card.

Try booting in Safe Mode. Safe Mode loads a minimal set of Apple-Only extensions (NOT including graphics acceleration extensions) so screen re-draw will be wonky and slow, but ultimately correct.

Safe mode takes defaults for everything possible, rather that using stored settings. If your combined display resolution settings are too high, these defaults may allow a picture (in reduced resolution) on each display.

Changes you make in Safe Mode will "stick" in regular mode.

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Answer 7

mdsalemi Author

Level 1

15 points

Mar 9, 2021 1:33 PM in response to Grant Bennet-Alder

I didn't actually set the resolution for anything; the [Dell] monitor automatically defaults to the 3840 x 2160, just as the Cinema Display defaults to 2160 x 1440. Once the system is up and running, of course, you have the ability to change the monitor's resolution. I cannot seem to find any information on the Radeon HD 7970 that would indicate it cannot drive multiple monitors at any specific resolution. I certainly can understand that if I've exceeded the GPU's capabilities, it won't work. But I cannot seem to find anything that lists number of monitors versus display resolution to see if I've hit any limits.

I will try and boot in safe mode with both Dell's attached, and see if I can set the resolution a bit lower on them and see if it will hold. I also "fixed" the display input on the monitor from "auto" (which scans for a signal) to default to DP and see if that works too.

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Answer 8

Johnb-one

Level 6

9,180 points

Mar 9, 2021 2:27 PM in response to mdsalemi

Well.. i don’t have a ton of insight on this one... it does have the 2 position switch and it can drive up to 6 monitors via a DisplayPort 1.2 hub...max resolution is 2560 x 1600 for the XFX version of this card.. so i am presuming that is per output.. eg hdmi will do 2560 x

1600, either of the Displayports will do 2560 x 1600 and the dvi, using a dual link cable will do that. U should of course make sure you have hdmi 2.0 cable, DisplayPort 1.2 cable and whatever the most recent version of dvi is( haven’t used that in years though.. if u use a dvi-hdmi adapter, it should be dual-link and ACTIVE.. so maybe do that Dell EDID override thing i mentioned and check your cables

thats all i got, sorry.. apart from switchResX and zapping the pram 3x ..

john b

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Answer 9

mdsalemi Author

Level 1

15 points

Mar 9, 2021 2:41 PM in response to Johnb-one

By themselves, or together, when attached, neither one of the Dell monitors will allow the MacPro to boot up when either or both is attache via the DP cable. However, if I connect ONE Dell monitor with the HDMI, it will boot up, and display at 3840x2160 at 30HZ. I can then, with the power on, connect the 2nd Dell with the DP cable, and THEN it will work at 3840x2160 but at 60Hz.

I don't think it will boot up at all if I leave the DP cable connected, and try to restart. I may have to plug in the 2nd monitor after it's all up and running.

When it won't boot up with the two DP cables connected it will NOT boot in Safe Mode either. Just hangs up.

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Answer 10

Mar 9, 2021 4:39 PM in response to mdsalemi

You are seeing the card limit the refresh rate for one of the two 4K displays.

That suggests again that you are hitting the limits of the card's rasterizer/display-generators ability to pull bytes from RAM for display.

Memory bandwidth is limited, and running multiple displays with resolutions as high as 4K with 60Hz refresh is a tough job for a card, even one of this era.

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Answer 11

Johnb-one

Level 6

9,180 points

Mar 11, 2021 9:48 AM in response to mdsalemi

‘Tis maddening + frustrating to be sure, mdsalemi.. DP is capable of carrying audio + video as is HDMI... if you go to system preferences>> sound>> effects/alerts, under Outputs>> play through, HDMI output should be listed...if not, go to Audio MIDI setup( should be in Utilities folder) and set up an audio output there. Should also be set to 44 khz/48 khz , 16 bit, 2 channel, and crank the sliders all the way to the right( full volume) . If you hold down the “option” key on the Keyboard and click on the speaker icon at the top right-ish of your screen , It will show you all available audio/sound inputs and outputs. You also have to, using the monitors menu, go into sound and crank the volume up. That is all I have for you today. There is a kext out there to enable/fix/ reenable HDMI audio, but I’ll leave that for you discover and deal with.

john b

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Answer 12

Mar 11, 2021 10:34 AM in response to mdsalemi

I have been looking around for reviews and specs, and have been unable to find any that talk about the number and resolutions of displays supported (lots of information about how fast it computes and shades and plays games).

The other information I have been reading is all the complaining about the noise & heat generated by the MacBook Pro 16-in model, that uses comparable GDDR5 display memory and drives users NUTS with the fan noise because it throws so much heat with one or more 4K display.

Based on the time when that card was issued (circa 2012), it predates the rise of common, affordable 4K displays. That card is out of gas in terms of how many and how high resolutions it can support at pleasant refresh rates.

In my opinion, you are trying to get performance from that card that is simply beyond its capabilities. Your two displays at 2K displays were a great match for it, but two at 4K (a quadrupling of the number of pixels displayed) is just overwhelming (or you can attain it, but just barely if you 'trick' the card into those settings).

In my opinion, to run two displays that large, you need a more-capable graphics card.

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Answer 13

mdsalemi Author

Level 1

15 points

Mar 11, 2021 11:16 AM in response to Grant Bennet-Alder

Right. It's old. Got that. It can display very high res on two monitors but the monitors--not the card--simply refuse to allow the system to boot up.

However, it's the "last and final" card for the MacPro 5,1 that was true "Apple"; to be sure, there are some newer cards, and many of them quite costly, for gamers, bitcoin miners and what have you, that have to be "hacked" to work in a Mac. So, this is the last card I will get for this before retiring this computer.

What few specs I see on the card in terms of resolution, etc. I must be interpreting incorrectly. Or they are for different subsets of that card. I don't understand why the Mac won't boot up if connected by the DP.

JohnB, insightful on the sound, but no dice. The available options using both the Midi method, and the Sound Effects method only revealed Built-In Output (that's only Internal Speaker) and Built-In Line Out (that's only the audio out port on the front); there is no "send the sound out through the DP or HDMI cable" or something like it, and only when a Cinema Display is attached does the option "use display" show up for sound. Oh, well... Thanks for the help though...

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Will Not Boot with New Display Monitors!!??

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