SOLVED - dual monitor problem

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gonzo01
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SOLVED - dual monitor problem

Post by gonzo01 »

I have HD monitor (1920x1080) and a UHD (3840x....) I can only atach the UHD monitor via hdmi cable, though the hd monitor has VGB, DV and HDMI - this is connected by VGA as the pc's DVI and HDMI outputs are so close together that only 1 or the other can be attached.

PROBLEM. (1) if VGA ( 1920x1080 monitor) and HDMI ( UHD 3840 x..) are both attached at boot (Mint 17 MATE) and the monitor setup in Mint is for both to display 1920x1080, neither monitor "loads" as the VGA attached monitor shows "out of range".

It appears that Mint is trying to boot it into UHD mode (3840 x ...). Apparently VGA is loaded first.

Either monitor works fine on its own as long as it is the only one that has been plugged into the PC.

Is there some way to overcome this and force the UHD monitor to load first?

Problem (2)

In Addittion, todat I purchased an HDMI splitter - 1 in 2 out. This works fine except that both monitors display the same desktop - the PC loads at 1920x1080 for both, but Display Settings only shows the UHD monitor.

Is there a way to Stretch the one screen accross the two monitors?

Thanks
Last edited by gonzo01 on Tue Mar 17, 2015 2:49 am, edited 1 time in total.

vl1969
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Post by vl1969 »

IProblem 2 is a no go, if you use the splitter it will simply split the output, not give you 2 monitors.
Problem 1 however is different storry, first read the documenys for your video card, the reason the hdmi and dvi are so close together is that the card does not support 2 digital output to be used at the same time. Ie, only dvi or hdmi to ve used not both. You wouldn't believe how many cards I have laying arond collecting dust because of that.
Also in many cards have hdmi as primary port if monitor is connected, also most all of them support vga and digital port use but hdmi is still the primary for many of them although some switch to vga to primary boot if connected.

One more thing, since most cards default to hdmi port as primary the lowest resolution monitor needs tobe pluged in there. But that might not be too important, not sure.


One more thing to add, on boot you might still see the same picture on both monitors untill you actually boot Into OS. When logged in you can choose the primary mon. In display settings.

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AlbertP
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Re: dual monitor problem

Post by AlbertP »

gonzo01 wrote:PROBLEM. (1) if VGA ( 1920x1080 monitor) and HDMI ( UHD 3840 x..) are both attached at boot (Mint 17 MATE) and the monitor setup in Mint is for both to display 1920x1080, neither monitor "loads" as the VGA attached monitor shows "out of range".
Please open Terminal, run the following commands with both monitors connected and post the output:

Code: Select all

inxi -Gx
xrandr -q
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vl1969
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Post by vl1969 »

I forgot to add that vga does not support 1920x1080 res. Hence if both mon. Setup to it than whichever mon. Is connected to vga port it will be out of range.

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AlbertP
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Re: dual monitor problem

Post by AlbertP »

vl1969 wrote:I forgot to add that vga does not support 1920x1080 res.
Yes, VGA ports do support that resolution. Officially the maximum is at 2048×1536 @ 85 Hz, not all hardware supports that, but all VGA hardware I've encountered to date was able to display 1920x1080 correctly.
There may be equipment such as KVM switches, converter cables, etc. which is not certified for 1920x1080 resolution, but in practice these devices don't cause problems with high resolutions apart from perhaps a slightly unsharp image.

My old (2006) laptop can use a 1920x1080 screen for presentations with VGA, I've done that a few times already. It just can't use both screens (internal and VGA) at the same time with 3D acceleration because of a GPU limitation in the old hardware that limits the total horizontal resolution.
Also my dad is a daily user of a 1920x1080 LG monitor which he connects to his (modern) laptop using VGA.
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vl1969
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Post by vl1969 »

I have never see a vga connected pc that could run @ 1920x1080 and show good picture. Sorry. I tried 2 pc and a laptop and they all droped down the effective res to a lesser range or show a black screen. I guess it is all in video card.

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AlbertP
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Re: dual monitor problem

Post by AlbertP »

Sometimes there is a problem with detecting the right resolutions on a monitor - can often be worked around by generating a modeline for the resolution with cvt and adding that mode with xrandr (I think there are plenty of tutorials on the web for this). I wouldn't declare this a hardware limit until we know more about the hardware (graphics card, driver, xrandr output with detected resolutions).
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gonzo01
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Re: dual monitor problem

Post by gonzo01 »

Thanks for the replies - firstly - my bad - not VGA but DSUB

here is output from
inxi -Gx
xrandr -q
bill@bill-GA-MA785GM-US2H ~ $ inxi -Gx
Graphics: Card: Advanced Micro Devices [AMD/ATI] RS880 [Radeon HD 4200] bus-ID: 01:05.0
X.Org: 1.15.1 drivers: ati,radeon (unloaded: fbdev,vesa) Resolution: 1920x1080@60.0hz, 1920x1080@30.0hz
GLX Renderer: Gallium 0.4 on AMD RS880 GLX Version: 3.0 Mesa 10.1.0 Direct Rendering: Yes
bill@bill-GA-MA785GM-US2H ~ $ xrandr -q
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 8192 x 8192
VGA-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 598mm x 336mm
1920x1080 60.0*+
1680x1050 60.0
1600x900 60.0
1280x1024 75.0 60.0
1280x960 60.0
1280x800 59.8
1152x864 75.0
1280x720 60.0
1024x768 75.1 60.0
1024x576 60.0
832x624 74.6
800x600 75.0 60.3
640x480 75.0 60.0
720x400 70.1
DVI-0 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 608mm x 345mm
3840x2160 30.0 + 25.0 24.0 30.0 24.0
2560x1440 60.0
1920x1080 60.0 50.0 59.9 30.0* 24.0 30.0 24.0
1680x1050 59.9
1600x900 60.0
1280x1024 75.0 60.0
1440x900 59.9
1280x800 59.9
1152x864 75.0
1280x720 60.0 50.0 59.9
1024x768 75.1 70.1 60.0
832x624 74.6
800x600 72.2 75.0 60.3 56.2
720x576 50.0
720x480 60.0 59.9
640x480 75.0 72.8 66.7 60.0 59.9
720x400 70.1
bill@bill-GA-MA785GM-US2H ~ $

mobo has onboard graphics - not separate vid card.

monitors are:-

BENQ GW2750 HDMI ( 27 inch - connected to dsub- DSUB, DVI and HDMI inputs)-1920x1080 max res - primary display - left display
and
SAMSUNG UD590 ( 28 inch UHDMI - 2 HDMI inputs only + Display Port)- 3840x2160 max res - running at 1920x1080 ( secondary display) - right display

different display on both monitors - left monitor - benq - has desktop menus

Havent had problems with dual disp0lays until I added the UHDMI Samsung. Had forgotten about Xorg.conf and randr. System ( mint 17 64 bit) doesnt have an Xorg.conf file.

Advice please. I'd prefer the Samsung UHDMI at max res as primary display if possible.

Thanks again

AlbertP
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Re: dual monitor problem

Post by AlbertP »

Your GPU supports HDMI 1.3, which has a maximum resolution of 1920x1080@60Hz officially.
Linux apparently allows you to choose a higher resolution using the Displays tool, but I don't think it will work as your GPU is too old for it.

As of Mint 17, 4K / Ultra HD monitors are supported in the Radeon driver but at http://www.phoronix.com/scan.php?page=n ... px=MTQ1NzE a driver developer (Alex Deucher) makes clear that only the Radeon HD 6000 series and up, support it. From the 6000 series on HDMI 1.4 support was available.

To use the UHD monitor, I would consider getting a graphics card of the NVIDIA GTX 600 series and higher, or Radeon HD 6000 and higher, preferably with a DisplayPort connection on it.
Please note that there are cheap cards on the market based on old generations. According to Wikipedia this includes the 6350, 7350, 8350 and R5 210 which are rebrands of the Radeon HD 5450 card.
For NVIDIA, I think the GT 640 and higher, as well as GT 740 and higher and all of the 900 series, are compatible.
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gonzo01
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Re: dual monitor problem

Post by gonzo01 »

Albert5P, thanks for the reply and info.

I'm OK with the UHD monitor running at 1920x1080 - thats how I'm using it now - both monitors at same resolution.

I've determined that the problem I'm having is due to Grub 2.

If I boot my PC with both monitors on, the HD monitor shows "Out Of range" error and Grub menu fails to show - the UHD monitor remains blank. This is with multiple distros on the HD and Grub booting from this disk.

If I do the same with my new HD as the boot disk - I've tried it with UbuntuMate 14.10 - I still get the "Out Of range" message, but Grub runs ( nothing on screen) till it boots UbuntuMate and then the Desktop and Monitor config loads. Everything is then fine though the displays are duplicated but at 1920x1080.

Apparently I either need to alter something in Grub2 or use a different boot loader.

I'll investigate further.

AlbertP
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Re: dual monitor problem

Post by AlbertP »

If you finally get into the desktop, I think you can use the Displays program to disable mirroring. Be careful not to set the resolution above 1920x1080 on the UHD monitor there; if they are not mirrored the program might default to the screens' native resolutions. That program will save its data into the ~/.config/monitors.xml file which is read when you log in.

Grub can probably be fixed to one resolution in the /etc/default/grub file:

Code: Select all

gksudo gedit /etc/linuxmint/grub
This file contains a line:

Code: Select all

#GRUB_GFXMODE=640x480
To set a resolution, remove the # sign and enter the wanted resolution.
After saving this file, run this command to write the Grub configuration:

Code: Select all

sudo update-grub
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gonzo01
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Re: SOLVED - dual monitor problem

Post by gonzo01 »

All OK now thanks

edited /etc/default/grub

set GRUB_GFXMODE=800x600 (1280x720 didnt work)

ran sudo update-grub

rebooted

set monitor config via applet to non-duplicate (non-mirroring) displays at 1920x1080

All boots ok with both monitors attached.

Thanks again

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