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Author Topic: Guide: Dummy Plugs for Graphics Cards  (Read 14720 times)

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Offline SolidSnke

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Guide: Dummy Plugs for Graphics Cards
« on: May 09, 2013, 12:24:16 pm »
I think this is only relevant to Windows Systems, but somebody please correct me if I am wrong on Linux. I do run Linux and am very familiar with it, but not GPU and CGMiner side of it.

Anyways here it is and I hope it help. Also as a side note you can attach the crossfire cables, and disable the crossfire software in the AMD Control Panel and it will do the same thing.

If you want to run a GPU miner (CGMiner / BFGMiner / etc) with more than one graphics card connected, and if you are using any version of Windows, you will need a monitor attached to each graphics card, or use a dummy plug to make it seem so.

You need to tell Windows to spread the picture over all your graphics cards. Windows XP will happily assume each graphics card has a monitor attached and try to spread the picture over a monitor which you do not have. Windows Vista checks to make sure.

You can make a dummy plug using three resistors and either a 15-pin D-plug or a DVI-I to VGA adapter, which is included with most graphics cards. You can solder the resistors to the 15-pin D-plug, or simply stick them in the holes of the DVI-I to VGA adapter.

Here the link to the diagram you are going to need so you know where to put your resistors.

http://soerennielsen.dk/mod/VGAdummy/index_en.php is the diagram.

Actually, you can get away with only having the middle resistor, the one connecting pins 2 and 7. But at some future date it might not work and you won't remember why.

How does it work?
The graphics card sends separate picture information on three separate channels, red, green, and blue. Each of the three channels has a pair of pins
pin 1 is Red Signal
pin 2 is Green Signal
pin 3 is Blue Signal
pin 6 is Red Ground
pin 7 is Green Ground
pin 8 is Blue Ground

If there is a monitor attached, it takes a few milliamps of current from the
graphics card. The computer tests whether a current is flowing from
the Green Signal on pin 2. If there is, it is assumed that an old-fashioned
VGA or SVGA monitor is connected. The resistor connecting pins 2 and seven
causes the same amount of current to flow as a monitor would.

Why 75 ohms?
If you are sending water down a pipe, it flows smoother if the pipework is the same diameter all the way. If you are sending electricity at radio frequency, it flows smoother if all the components have the same impedance. Television gear has an impedance of 75 ohms.

In the UK, Maplin M75R metal oxide resistors are the easiest to buy, but the wire is a bit thin to stick in the holes of a DVI-I to VGA adapter. It is said that 1/2 watt carbon resistors have thicker wire that is just the right size. In the USA, 75 ohm resistors are harder to find. You can use 68 ohms or 82 ohms instead. Anything between 50 and 100 ohms will probably work. If you use less than 50, you will be drawing too much current, perhaps. If you use too high a value, perhaps not enough current will flow to simulate a monitor being connected.

It does not matter which end of a resistor is which. I have arranged mine like this so you can see the colors are the same, and the bodies stop the wires touching. You only need one dummy plug per graphics card, even if it has two monitor sockets. Windows tries to detect what model of monitor is attached, and fails. Windows XP calls it a "Default Monitor" and Vista calls it a "non-generic pnp monitor".







Close up of Maplin M75R resistor. violet, green, black, gold, brown. The top three colors should be the same whichever type you buy. The other two colors show the tolerance, which does not matter.



Offline gavlor

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #1 on: May 09, 2013, 12:32:04 pm »
Nice guide .... I was wondering about this myself.

I think this has been sorted out in software / driver updates as Im not using them in Win 7

Offline mrp1

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #2 on: May 09, 2013, 01:39:09 pm »
Great guide, Thanks...  I may need it as I try a linux option on an upcomming reg.   

My Win7 machine currently has (3) 7950's and NO dummy plugs - all are working.    I'll update as I add (2) , maybe (3) more to this reg.

Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #3 on: May 09, 2013, 02:49:31 pm »
Hi Solid,

Great guide and post. Thanks for sharing!  :)

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Offline scheved

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #4 on: May 09, 2013, 04:04:20 pm »
yeah I dont use dummy plugs either. No monitors plugged into either of my cards :)  Connect to my rig over UltraVNC

Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #5 on: May 09, 2013, 04:08:33 pm »
yeah I dont use dummy plugs either. No monitors plugged into either of my cards :)  Connect to my rig over UltraVNC

Cool, I was wondering if VNC would be enough to kick start the cards as to being on. I guess in theory you think it would. :)
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Offline degoba

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #6 on: May 09, 2013, 11:20:01 pm »
You do not need a dummy plug to run on Linux.

Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #7 on: May 10, 2013, 02:58:10 am »
Degoba,

What is the best way to mine without a dummy plug on linux if you are using SSH and are not running VNC? I get GPU not found messages if I do not have a monitor plugged into the computer. I am almost never at the computer, but remotly logging in via SSH. Is there another way to get the GPU to come online without the dummy plugs, monitors or VNC?

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Offline lobhater

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #8 on: May 19, 2013, 02:19:15 am »
First make sure you have "export DISPLAY=:0"  (no quotes) at the top of your start up script or be sure to enter it every time before you mine.  This is a MUST if you have more than 1 card.  Try this first, if it doesn't do the trick do the following steps.

I agree I am running several rigs on Ubuntu with 2 or more cards and a dummy plug is not needed.  There are a couple of different options to get the additional cards to work.  The easiest if you have direct keyboard, mouse and monitor connected to the rig you go to the Admin Catalyst Control Panel, under Display Manager or Display Options( i cant remember which one and am not around it to check) it will list all of your cards.  The main card will show as active and "single monitor display" however the additional cards will show up but will not be active.  There will be a drop down menu to enable "multi-monitor display," select this option on the 2nd and each additional card.  Click "OK" it will tell you that you have to reboot.  After you restart the computer cgminer will happily mine on all cards without a dummy plus.  The second option is fairly easy too and great if you can only SSH like myself.

Pull up a shell and enter the following commands, it will back up your Xorg automatically so no worries their either.

sudo aticonfig –initial
sudo aticonfig –adapter=ALL –initial              (you may need to use amdconfig instead of aticonfig depending on your config)
sudo reboot
 
Regardless of which option you use be sure to add "export DISPLAY=:0" in your script or make it a habit to enter it before mining.



I hope this helped, if it didn't please paste the output of the following command here or pastebin.com the output and link it below.  I will be happy to help more if i can.

export DISPLAY=:0
fglrxinfo
cat /etc/X11/xorg.conf
cgminer -n


Also please past your config file and start up script.  Remove username and password if you are worried about people seeing it
1 PowerColor 7950 / 5 Gigabyte 7870s / 1 Gigabyte 7850 all hashing together @ 3.24 mh/s



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Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #9 on: May 22, 2013, 02:07:27 pm »
Hi lobhater,

Thanks for this advice. I will give it a try tonight. Or when all this work stuff stops coming to my desk. : )

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Offline Thrash

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #10 on: May 22, 2013, 04:58:43 pm »
sudo aticonfig –initial
sudo aticonfig –adapter=ALL –initial              (you may need to use amdconfig instead of aticonfig depending on your config)
sudo reboot
 
Regardless of which option you use be sure to add "export DISPLAY=:0" in your script or make it a habit to enter it before mining.

The above is  the key. I will bet it takes care of it. I'm running Debian so I use coldreboot instead of reboot but gives the same result.
-- Thrash

Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #11 on: May 23, 2013, 01:40:35 am »
I'm going to give this a try on Xubuntu in a little bit.
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Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #12 on: May 23, 2013, 05:18:48 pm »
First make sure you have "export DISPLAY=:0"  (no quotes) at the top of your start up script or be sure to enter it every time before you mine.  This is a MUST if you have more than 1 card.  Try this first, if it doesn't do the trick do the following steps.

I agree I am running several rigs on Ubuntu with 2 or more cards and a dummy plug is not needed.  There are a couple of different options to get the additional cards to work.  The easiest if you have direct keyboard, mouse and monitor connected to the rig you go to the Admin Catalyst Control Panel, under Display Manager or Display Options( i cant remember which one and am not around it to check) it will list all of your cards.  The main card will show as active and "single monitor display" however the additional cards will show up but will not be active.  There will be a drop down menu to enable "multi-monitor display," select this option on the 2nd and each additional card.  Click "OK" it will tell you that you have to reboot.  After you restart the computer cgminer will happily mine on all cards without a dummy plus.  The second option is fairly easy too and great if you can only SSH like myself.

Pull up a shell and enter the following commands, it will back up your Xorg automatically so no worries their either.

sudo aticonfig –initial
sudo aticonfig –adapter=ALL –initial              (you may need to use amdconfig instead of aticonfig depending on your config)
sudo reboot
 
Regardless of which option you use be sure to add "export DISPLAY=:0" in your script or make it a habit to enter it before mining.



I hope this helped, if it didn't please paste the output of the following command here or pastebin.com the output and link it below.  I will be happy to help more if i can.

export DISPLAY=:0
fglrxinfo
cat /etc/X11/xorg.conf
cgminer -n


Also please past your config file and start up script.  Remove username and password if you are worried about people seeing it

Hi Lobhater,

Thanks for the detailed instructions. I have tried your suggestions but my computer comes back with a lot of errors. I am running Xubuntu 12.10.

Here is the output from my command line...

hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ sudo aticonfig --initial
Found fglrx primary device section
Using /etc/X11/xorg.conf
Saving back-up to /etc/X11/xorg.conf.fglrx-4
hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ sudo aticonfig -initial
No layout section was found in the file: '/etc/X11/xorg.conf'.
Please run 'aticonfig --initial' first or modify your configuration file manually and run aticonfig again.
aticonfig: parsing the command-line failed.
hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ sudo aticonfig -adapter=ALL -initial
aticonfig: invalid option -- 'a'
aticonfig: parsing the command-line failed.
hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ sudo aticonfig --adapter=ALL -initial
No layout section was found in the file: '/etc/X11/xorg.conf'.
Please run 'aticonfig --initial' first or modify your configuration file manually and run aticonfig again.
aticonfig: parsing the command-line failed.
hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ sudo aticonfig --adapter=ALL --initial
Found fglrx primary device section
Found fglrx primary device section
Using /etc/X11/xorg.conf
Saving back-up to /etc/X11/xorg.conf.fglrx-5
hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$


Also here is the info you requested.......

hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ fglrxinfo
Error: unable to open display (null)


hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ cat /etc/X11/xorg.conf

Section "ServerLayout"
        Identifier     "aticonfig Layout"
        Screen      0  "aticonfig-Screen[0]-0" 0 0
        Screen         "aticonfig-Screen[1]-0" RightOf "aticonfig-Screen[0]-0"
EndSection

Section "Module"
EndSection

Section "Monitor"
        Identifier   "aticonfig-Monitor[0]-0"
        Option      "VendorName" "ATI Proprietary Driver"
        Option      "ModelName" "Generic Autodetecting Monitor"
        Option      "DPMS" "true"
EndSection

Section "Monitor"
        Identifier   "aticonfig-Monitor[1]-0"
        Option      "VendorName" "ATI Proprietary Driver"
        Option      "ModelName" "Generic Autodetecting Monitor"
        Option      "DPMS" "true"
EndSection

Section "Device"
        Identifier  "aticonfig-Device[0]-0"
        Driver      "fglrx"
        BusID       "PCI:1:0:0"
EndSection

Section "Device"
        Identifier  "aticonfig-Device[1]-0"
        Driver      "fglrx"
        BusID       "PCI:6:0:0"
EndSection

Section "Screen"
        Identifier "aticonfig-Screen[0]-0"
        Device     "aticonfig-Device[0]-0"
        Monitor    "aticonfig-Monitor[0]-0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
        EndSubSection
EndSection

Section "Screen"
        Identifier "aticonfig-Screen[1]-0"
        Device     "aticonfig-Device[1]-0"
        Monitor    "aticonfig-Monitor[1]-0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
        EndSubSection
EndSection

hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ nano mine_digicoins.sh

#!/bin/sh
export DISPLAY=:0
export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1
cd /home/hafminer-01/cgminer-2.11.4-x86_64-built


#NO STRATUM
# 15 800k max
./cgminer --scrypt -I 15 -o http://www.digicoinpool.com:8388 -u [username] -p [password]











« Last Edit: May 23, 2013, 06:01:41 pm by spincycle »
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Offline lobhater

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #13 on: May 24, 2013, 03:18:34 am »
Sorry its late, when i get to work tomorrow i will take a while and really pick through what you posted, but with a quick glance i noticed a couple things. 

sudo aticonfig --initial    <-- the first time this command ran successfully, but then you can it again but with only a single '-' before initial. which is where you first encountered an error.  Why the change in command?


The below error was caused because you did not do the 'export DISPLAY=:0' command first

hafminer-01@HAF-01:~/cgminer-2.11.4-x86_64-built$ fglrxinfo
Error: unable to open display (null)



I think most of these errors were cause by syntax errors.  A missed dash here a missed dash there,  ( Damn computers, so picky ;) )

So copy and paste the below commands exactly as they are below:

sudo aticonfig –initial
sudo aticonfig –adapter=ALL –initial
(PASTE RESULTS TO A NEW RESPONSE)

sudo reboot

export DISPLAY=:0
fglrxinfo
(PASTE RESULTS TO A NEW RESPONSE)


reboot and rerun your startup script again, i work about 9am MST and will get back to toy shortly after i get settled
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Offline spincycle

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Re: Guide: Dummy Plugs for Graphics Cards
« Reply #14 on: May 24, 2013, 04:58:27 pm »
Thanks Lobhater. I will give those commands a try, word for word. I think I changed the command because I was having a hard time with the initial command. But I will give it another go.

Thanks again,

Spin

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