OK so I have been going at this problem hammer and tong for 6 days now (and over two weeks in a previous attempt).My problem is setting up Linux Mint with an external monitor plugged into my laptop.I have tried possibly every suggestion I could find online without success. And now I am ready to break my laptop for trying and failing!My System and HardwareLaptop: Asus X5DClspci | grep -i vga output: 01:00.0 VGA compatible controller:Silicon Integrated Systems [SiS] 771/671 PCIE VGA Display Adapter(rev 10)External monitor: ViewSonic VX912xrandr output: xrandr: Failed to get size of gamma for output defaultScreen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768default connected primary 1024x768+0+0 0mm x 0mm1024x768       76.0* 1504x1200_60.00 (0x1ab)  151.4MHz    h: width  1504 start 1608 end 1768 total 2032 skew    0 clock   74.5KHz    v: height 1200 start 1201 end 1204 total 1242           clock   60.0Hzsudo lshw -C video output: *-display UNCLAIMED   description: VGA compatible controller   product: 771/671 PCIE VGA Display Adapter   vendor: Silicon Integrated Systems [SiS]   physical id: 0   bus info: pci@0000:01:00.0   version: 10   width: 32 bits   clock: 66MHz   capabilities: pm agp agp-3.0 vga_controller cap_list   configuration: latency=0   resources: memory:d0000000-dfffffff memory:fe9e0000-fe9fffff ioport:dc00(size=128)What I have tried alreadyEditing /etc/X11/xorg.conf many times and sometimes X wouldn't start so I had to undo my changes from tty terminal and restart. Here is my current xorg.conf: Section ServerLayout    Identifier     X.org Configured    Screen         Screen0 LeftOf Screen1EndSectionSection Monitor    Identifier   Configured Monitor    VendorName   Monitor Vendor    ModelName    Monitor Model    HorizSync 28-72    VertRefresh 43-60EndSectionSection Device    Identifier  Card0    Driver      sis    BusID       PCI:1:0:0EndSectionSection Screen    Identifier Screen0    Device     Card0    Monitor    Monitor0    SubSection Display        Viewport   0 0        Depth     1    EndSubSection    SubSection Display        Viewport   0 0        Depth     4        Modes      900x675 1024x768 1280x960 1400x1050    EndSubSection    SubSection Display        Viewport   0 0        Depth     8        Modes      900x675 1024x768 1280x960 1400x1050    EndSubSection    SubSection Display        Viewport   0 0        Depth     15        Modes      900x675 1024x768 1280x960 1400x1050    EndSubSection    SubSection Display        Viewport   0 0        Depth     16        Modes      900x675 1024x768 1280x960 1400x1050    EndSubSection    SubSection Display        Viewport   0 0        Depth     24        Modes      900x675 1024x768 1280x960 1400x1050    EndSubSectionEndSectionSection Screen    Identifier Screen1    Device     Card0    Monitor    Monitor0    SubSection Display        Viewport   0 0        Depth     1        Modes      1280x1024 1500x1200 1640x1312    EndSubSection    SubSection Display        Viewport   0 0        Depth     4        Modes      1280x1024 1500x1200 1640x1312    EndSubSection    SubSection Display        Viewport   0 0        Depth     8        Modes      1280x1024 1500x1200 1640x1312    EndSubSection    SubSection Display        Viewport   0 0        Depth     15        Modes      1280x1024 1500x1200 1640x1312    EndSubSection    SubSection Display        Viewport   0 0        Depth     16        Modes      1280x1024 1500x1200 1640x1312    EndSubSection    SubSection Display        Viewport   0 0        Depth     24        Modes      1280x1024 1500x1200 1640x1312    EndSubSectionEndSection`I have added the following .conf files to /usr/share/X11/xorg.conf.d:41-built-in-monitor.conf which contains:    Section Monitor        Identifier   Monitor0        VendorName   Built in Monitor        ModelName    Model Unknown        HorizSync       28.0 - 70.0        VertRefresh     56.0 - 75.0    EndSection42-second-vga-monitor.conf which contains:    Section Monitor        Identifier   Monitor1        VendorName   ViewSonic        ModelName    VX912        Option       RightOf  Monitor0        HorizSync       28.0 - 70.0        VertRefresh     56.0 - 75.0    Endsection50-video.conf which contains:    Section Device        Identifier Device2        Option  Monitor-Built-In Monitor0        Option  Monitor-VGA      Monitor1        Driver sis    EndSectionsudo update-pciidsgtf 1500 1200 60 -xoutput: # 1504x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 151.42 MHzModeline 1504x1200_60.00  151.42  1504 1608 1768 2032  1200 1201 1204 1242  -HSync +Vsyncxrandr --newmode  1504x1200_60.00  151.42  1504 1608 1768 2032 1200 1201 1204 1242  -HSync +Vsync output: xrandr: Failed to get size of gamma for output defaultX Error of failed request:  BadName (named color or font does not exist)Major opcode of failed request:  140 (RANDR)Minor opcode of failed request:  16 (RRCreateMode)Serial number of failed request:  19Current serial number in output stream:  19xrandr --addmode VGA1 1504x1200_60.00 output: xrandr: Failed to get size of gamma for output defaultxrandr: cannot find output VGA1xrandr --output VGA1 --mode 1504x1200_60.00 output: xrandr: Failed to get size of gamma for output defaultwarning: output VGA1 not found; ignoringAnd many more suggestions I found, in fact I'e tried that many things I could not list them here even if I could remember!Mate Monitor Preferences does not recognize external monitor (obviously).Arandr acts as though I only have the 'default' monitor.My system is displaying on both screens but not seperately, as in its the same on both monitors, so the monitor works and the VGA adapter works and the graphics card can output to both, just not as a proper dual monitor setup.If anyone knows what exactly is ~/.config/monitors.xml for? 
Dual monitor setup in Linux Mint 17.2 Rafaela
linux mint;x11;xorg;dual monitor;asus