I recently purchased a BenQ W600+ projector that I'd like to use with my ThinkPad T410 with Nvidia graphics running Ubuntu 12.10. The native resolution of the projector is 1280x720 (i.e. 720p), but I haven't been able to configure the Nvidia driver to actually use this resolution. The projector is connected to the VGA port. The driver is nvidia-current (I think).

Here are the resolutions offered by the "Displays" system settings. Note that 1280x720 is not listed: Displays setting window

I followed the directions under "Adding undetected resolutions" at wiki.ubuntu.com, but they lead to an error:

xrandr --newmode "1280x720"x0.0   74.25  1280 1390 1430 1650  720 725 730 750 -hsync -vsync 
xrandr --addmode VGA-0 1280x720x0.0

Here's the error message from the second xrandr command:

X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  39
  Current serial number in output stream:  40

I also see this error message in /var/log/Xorg.0.log:

[  2284.687] (WW) NVIDIA(GPU-0): Unable to read EDID for display device CRT-0
[  2284.687] (**) NVIDIA(0): Using HorizSync/VertRefresh ranges from the EDID for display
[  2284.687] (**) NVIDIA(0):     device CRT-0 (Using EDID frequencies has been enabled on
[  2284.687] (**) NVIDIA(0):     all display devices.)

I have another machine, a ThinkPad T510, with Intel graphics and running an earlier release of Ubuntu. On that machine the projector works fine, and the following appears in the Xorg logfile:

(II) intel(0): EDID vendor "BNQ", prod id 52737
(II) intel(0): Using hsync ranges from config file
(II) intel(0): Using vrefresh ranges from config file
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "1280x720"x0.0   74.25  1280 1390 1430 1650  720 725 730 750 -hsync -vsync (45.0 kHz)

The nvidia-settings program is similarly unhelpful. The "Acquire EDID" option is grayed out:

nvidia-settings screenshot

And it also doesn't offer the 1280x720 resolution:

enter image description here

I don't have any /etc/X11/xorg.conf file. I did try running nvidia-xconfig to create an xorg.conf file, but that seemed to make everything much worse: the projector came up only in 640x480, and the mouse cursor would get "stuck" on one of the displays. When X starts with this xorg.conf file, I also get this error message popup box:

enter image description here

How can I get the projector to work at 1280x720 on my T410?



After many hours of blindly fooling around with xorg.conf and xrandr, I found a solution that works.

The problem appears to be:

  1. The Nvidia driver insists on using EDID data from the display rather than anything set by xrandr or in xorg.conf.
  2. For some reason the Nvidia driver couldn't read the EDID data from my projector.

Thus, the solution is to provide an EDID override. I couldn't find one for my particular display, but I was able to find one for some other 720p projector. It works!

After getting the EDID file and putting it some place, it's installed in the xorg.conf file by adding a line like this to the "Screen" section of xorg.conf:

Option         "CustomEDID" "CRT-0:/path/to/edid.bin"

Here "CRT-0" is where the projector is connected: to the VGA port.

One more additional complication is that I couldn't actually find a binary EDID file. Instead, by searching for "720p EDID file", I found some .INF files that contain EDID information extracted by some Windows program. These are Windows .ini format files. They contain the actual EDID information in a block that looks like this:

;Base EDID

To turn that into a binary file, I wrote the following tiny Python script:


# first item was 0x01

s = "0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00,0x3D,0xCB,0x81,0x07,0x00,0x00,0x00,0x00,0x00,0x11,0x01,0x03,0x80,0x6E,0x3E,0x78,0x0A,0xEE,0x91,0xA3,0x54,0x4C,0x99,0x26,0x0F,0x50,0x54,0x20,0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x1D,0x00,0x72,0x51,0xD0,0x1E,0x20,0x6E,0x28,0x55,0x00,0x53,0x6F,0x42,0x00,0x00,0x1E,0x01,0x1D,0x80,0x18,0x71,0x1C,0x16,0x20,0x58,0x2C,0x25,0x00,0x53,0x6F,0x42,0x00,0x00,0x9E,0x00,0x00,0x00,0xFC,0x00,0x54,0x58,0x2D,0x53,0x52,0x38,0x30,0x35,0x0A,0x20,0x20,0x20,0x20,0x00,0x00,0x00,0xFD,0x00,0x3B,0x3D,0x1E,0x2E,0x08,0x00,0x0A,0x20,0x20,0x20,0x20,0x20,0x20,0x01,0x5A"

s = "".join(map(lambda x : chr(int(x, 16)), s.split(",")))

f = open("edid.bin", "w")

Note that you have to remove the first three fields from the line in the .inf file: "HKR,EDID_OVERRIDE,"0",0x01".

To verify that the resulting EDID file was valid, I used parse-edid (part of the read-edid package):

tobin@thinktop:~/pathname/$ parse-edid edid.bin
parse-edid: parse-edid version 2.0.0
parse-edid: EDID checksum passed.

    # EDID version 1 revision 3
Section "Monitor"
    # Block type: 2:0 3:fc
    Identifier "TX-SR805"
    VendorName "ONK"
    ModelName "TX-SR805"
    # Block type: 2:0 3:fc
    # Block type: 2:0 3:fd
    HorizSync 30-46
    VertRefresh 59-61
    # Max dot clock (video bandwidth) 80 MHz
    # DPMS capabilities: Active off:no  Suspend:no  Standby:no

    Mode    "1280x720"  # vfreq 60.000Hz, hfreq 45.000kHz
        DotClock    74.250000
        HTimings    1280 1390 1430 1650
        VTimings    720 725 730 750
        Flags   "+HSync" "+VSync"
    Mode    "1920x540"  # vfreq 60.053Hz, hfreq 33.750kHz
        DotClock    74.250000
        HTimings    1920 2008 2052 2200
        VTimings    540 542 547 562
        Flags   "Interlace" "+HSync" "+VSync"
    # Block type: 2:0 3:fc
    # Block type: 2:0 3:fd

So it appeared valid. Indeed, after restarting the X server, I was able to go into the Ubuntu Display settings and click "Detect Displays". It sees my fake 'ONKYO Corporation 50"' display and happily drives it at 1280x720. Required one more X reset to get everything working.

...And this is why we love Linux. (-:


You need to use the nvidia-settings for that. Not the Display Settings that Ubuntu offers. This is because the drivers are proprietary and not very friendly when it comes to using stuff like this. Before reading I highly suggest you read How do I install the Nvidia drivers?

Here is my test case:

I have an Epson video beam and the computer's monitor. Without the video beam it shows like this:

enter image description here

Now, connecting the video beam and clicking on Detect Displays in the Nvidia Display Configuration section shows the following:

enter image description here

I then drag the layout boxes around (The ones that represent the video beam and Monitor) to my liking and resolution. So they look like this:

enter image description here

Make sure you select the one you want to see as default as the Primary Display at the bottom of the options.

Now if you want to make both show the same thing you need to first make sure both screen support the same resolution or at least a common one. In my case I have this:

  • Video beam supports all 4:3 resolutions up to 1280x1024

  • TV monitor supports all 16:9 resolutions up to 1920x1080

So what I need to do is find a highest resolution where both meet. Mine was 1280x720 or 1024x768. To do this easier, select the Video Beam and select Clone as shown in the following image in the "Position" option:

enter image description here

Make sure the other Monitor (The TV Monitor in my case) is the Primary one. At least one of them has to be the Primary and the other the Clone to work.

Now start selecting the resolution you need. If you get a wrong one press ESC and repeat until you find the best one for the Monitor and Video Beam.

Again, all of this has to be done via the Nvidia Settings Panel. Not all Nvidia cards will work with the Display Settings that Ubuntu has since the proprietary drivers are not yet friendly enough to let the Display Settings work correctly.

  • Thank you for the effort, however I don't think your answer addresses my question. (1) I am already running the proprietary Nvidia drivers, version 310.14; (2) The resolution I want does not appear in the selection box; and (3) I don't want to clone the displays. – nibot May 16 '13 at 19:49
  • @nibot can you select the next higher resolution and see that it works? If yes, then you can customize the viewport through the nvidia settings. If you click the advanced button you should see some options that show the resolution and you can modify this. Similar to something I mentioned at the bottom of this answer askubuntu.com/questions/80324/… – Luis Alvarado May 16 '13 at 20:28

It was the VGA cable!

I replaced the 3 meter BELKIN cable with a shorter and possibly higher-quality one, and now the Nvidia drivers automatically detect the BenQ projector and everything works.

According to one Amazon reviewer, the BELKIN cable is defective by design:

It's a well constructed cable, but is lacking pin 9 and doesn't pass the EDID data of plug and play monitors/tv's so wouldn't recommend it's purchase.

I tested using a Dell Dimension 8250 (ATI 9700) and a Dell Vostro 1500 (NVIDIA 8600) and a Samsung LE40B652 40" TV that was detected as a "Non-Plug and Play" Monitor and correctly displayed resolutions upto 1440 x 900 @ 60Hz with this VGA cable.

The picture quality is good enough but it's basic requirement that a VGA cable support the plug and play features of XP/Vista these days.

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