[SUCCESS] ASUS ROG Maximus IX Hero - i7-7700K - 32GB RAM - Intel HD630 > EVGA GTX 1070 SC2 > AMD Sapphire RX580 Pulse

[JCMunsonII]

Maybe homogeneous connections are key too? And, perhaps same resolution?

 

[Bob_the_Tomato]

Maybe homogeneous connections are key too? And, perhaps same resolution?

I have to admit that I've not EVER said "homogenous connections" in my life.... lol
Do you mean something like use the same type of connection? Like all Display Port?

I have mixed them in the past. I had a temporary video card that forced me to use HDMI but I could not get the 4K to work. BUT the machine always booted with both monitors plugged in. I had another video card that would boot with two monitors attached but would fart and seize the Hack if I kept the second monitor turned on. I retired that card after two attempts at RMA'ing it. EVGA did replace the first card (a GTX980 KingPin edition and gave me a GTX980Ti in replacement but that didn't help either!) That Ti card is sitting in a box next to my computer... replace by the GTX1080Ti which boots both monitors no problems.

 

[JCMunsonII]

I think, for testing reasons, as much as can be the same, should be. All DP or all HDMI, all at same res, etc., etc. If that works, try "screwing it up."

 

[iSlaker]

I have two connected via Display Port and one via DVI. Haven't managed to get any permutation of those connections to work, although I've not tried any connected via HDMI. Not a bad idea.

I wonder if the card manufacturer, the motherboard bios or even the type of cables used affect the whole process more than we know? I can't think of any other reason why it works for me but not you. My BIOS is basically on default mode, apart from the CPU turbo thing being disabled. The monitors are plugged in via Display Port to DVI cables (maybe not having to carry sound makes a difference? I'm just speculating, really.) And my graphics card is made by Gigabyte.

Talking to a friend who's also an enthusiast he didn't seem too impressed with the monitors situation but he was suprised I managed to get it to work without disconnecting anything from the USB ports. I remember years ago playing with Lion or Leopard after hours of crashes I realised what was causing problems was an Xbox controller receiver plugged in.

 

[bombardier]

If I get time over the next few days I'll try some different permutations again. I suspect that it's just going to be one of those things I need to live with running a Hackintosh!

 

[Bob_the_Tomato]

If you are going to use HDMI you must pay attention to the revision level. There are several revisions based on their respective capabilities. Most HDMI cable will not allow 4K signals to pass through, or they are symply incapable. Only version 2.1 will handle 4K in all refresh rates.
See https://en.m.wikipedia.org/wiki/HDMI#Version_comparison

 

[bombardier]

I think, for testing reasons, as much as can be the same, should be. All DP or all HDMI, all at same res, etc., etc. If that works, try "screwing it up."

I finally found the time yesterday to properly investigate this issue. Here's what my original setup was:

Dell 27": DP out > DP in
Viewsonic 22": DVI out > DVI in
Dell 19": DVI out > DP in (via cable, rather than adapter)

Removing the Viewsonic DVI from the equation I could get the two Dells to come on at boot, but even then only if they were in the two DP ports of the 1070 that are paired on the left hand side as you look at them. If one of them was in the single DP next to the HDMI it would black screen shortly after the Apple logo.

Introducing the DVI back in resulted in the Apple logo and progress bar being 'stuck' at half way, even though the machine was booting in the background.

Following your lead above, JC, I ordered another DVI > DP cable (I have no recollection of buying one when I first set this up, although I must have done for Dell 19"!) to have all monitors connected via the same method. Connected the Viewsonic, and all working on boot! I'm so happy Now, connections are thus:

Dell 27": DP out > DP in
Viewsonic 22": DVI out > DP in (via cable, rather than adapter)
Dell 19": DVI out > DP in (via cable, rather than adapter)

 

[JCMunsonII]

Fantastico!

 

[bombardier]

Early days, but the move to 18,3 seems like it was a good one, too. I haven't noticed the graphical glitches I was getting, nor the odd momentary pause or slowdown.

 

[JCMunsonII]

Also fantastic!