Second monitor black screen with Mouse Pointer

[Harri Hannula]

My system info:
inxi -F
System: Host: h-HP-Compaq-dx2450-Microtower-PC Kernel: 4.15.0-20-generic x86_64
           bits: 64
           Desktop: MATE 1.20.1 Distro: Ubuntu 18.04 LTS
Machine: Device: desktop System: Hewlett-Packard product: HP Compaq dx2450 Microtower PC serial: N/A
           Mobo: PEGATRON model: 2A72h v: 3.02 serial: N/A
           BIOS: Phoenix v: 5.19 date: 11/03/2008
CPU: Dual core AMD Athlon 64 X2 5200+ (-MCP-) cache: 1024 KB
           clock speeds: max: 2700 MHz 1: 2200 MHz 2: 2200 MHz
Graphics: Card-1: NVIDIA C61 [GeForce 6150SE nForce 430]
           Card-2: NVIDIA NV43 [GeForce 6600]
           Display Server: x11 (X.Org 1.19.6 )
           drivers: nouveau (unloaded: modesetting,fbdev,vesa)
           Resolution: 1280x1024@60.02hz, 2560x1024@60.00hz
           OpenGL: renderer: NV4C version: 2.1 Mesa 18.0.0-rc5
Audio: Card NVIDIA MCP61 High Def. Audio driver: snd_hda_intel
           Sound: Advanced Linux Sound Architecture v: k4.15.0-20-generic
Network: Card: NVIDIA MCP61 Ethernet driver: forcedeth
           IF: enp0s7 state: up speed: 100 Mbps duplex: full
           mac: 00:22:64:be:80:84
Drives: HDD Total Size: 250.1GB (3.0% used)
           ID-1: /dev/sda model: WDC_WD2500AAJS size: 250.1GB
Partition: ID-1: / size: 229G used: 7.0G (4%) fs: ext4 dev: /dev/sda1
RAID: No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors: System Temperatures: cpu: 11.0C mobo: N/A gpu: 68.0
           Fan Speeds (in rpm): cpu: N/A
Info: Processes: 161 Uptime: 1:44 Memory: 1068.9/3818.4MB
           Client: Shell (bash) inxi: 2.3.56

Monitor info:
xrandr
Screen 0: minimum 320 x 200, current 3840 x 1024, maximum 4096 x 4096
VGA-1 connected primary 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
   1280x1024 60.02*+ 75.02
   1152x864 75.00
   1024x768 75.03 60.00
   800x600 75.00 60.32
   640x480 75.00 59.94
   720x400 70.08
VGA-1-2 connected 2560x1024+1280+0 (normal left inverted right x axis y axis) 410mm x 310mm
   2688x1682 59.99 49.99
   2728x1538 49.99
   2560x1024 60.00*
   1600x1200 60.00
   2048x768 85.00 75.03 60.00
   1368x1026 49.96
   1280x1024 85.02 75.02 60.02
   1280x960 85.00 60.00
   1024x768 85.00 75.03 60.00
   800x600 85.06 75.00 60.32
   640x480 85.01 75.00 59.94
DVI-I-1-1 disconnected (normal left inverted right x axis y axis)
TV-1-1 disconnected (normal left inverted right x axis y axis)
  1280x1024 (0xbe) 135.000MHz +HSync +VSync
        h: width 1280 start 1296 end 1440 total 1688 skew 0 clock 79.98KHz
        v: height 1024 start 1025 end 1028 total 1066 clock 75.02Hz
  1280x1024 (0xbd) 108.000MHz +HSync +VSync
        h: width 1280 start 1328 end 1440 total 1688 skew 0 clock 63.98KHz
        v: height 1024 start 1025 end 1028 total 1066 clock 60.02Hz
  1024x768 (0xc0) 78.750MHz +HSync +VSync
        h: width 1024 start 1040 end 1136 total 1312 skew 0 clock 60.02KHz
        v: height 768 start 769 end 772 total 800 clock 75.03Hz
  1024x768 (0x45) 65.000MHz -HSync -VSync
        h: width 1024 start 1048 end 1184 total 1344 skew 0 clock 48.36KHz
        v: height 768 start 771 end 777 total 806 clock 60.00Hz
  800x600 (0xc1) 49.500MHz +HSync +VSync
        h: width 800 start 816 end 896 total 1056 skew 0 clock 46.88KHz
        v: height 600 start 601 end 604 total 625 clock 75.00Hz
  800x600 (0x46) 40.000MHz +HSync +VSync
        h: width 800 start 840 end 968 total 1056 skew 0 clock 37.88KHz
        v: height 600 start 601 end 605 total 628 clock 60.32Hz
  640x480 (0xc2) 31.500MHz -HSync -VSync
        h: width 640 start 656 end 720 total 840 skew 0 clock 37.50KHz
        v: height 480 start 481 end 484 total 500 clock 75.00Hz
  640x480 (0x49) 25.175MHz -HSync -VSync
        h: width 640 start 656 end 752 total 800 skew 0 clock 31.47KHz
        v: height 480 start 490 end 492 total 525

VGA-1-2 is black screen with mouse pointer

[Opimus Honos (ophonos)]

Install a proprietary NVIDIA driver.

[Neptilo (neptilo)]

Hello. I tried installing a proprietary Nvidia driver but the result was even worse: my second screen wasn't even detected.

[Sam (samshiles)]

I had the problem using both the nouveau driver (black screen with only a mouse pointer) and the nvidia driver (screen was not detected at all). I suspected the problem was being cause by secureboot (like so many problems are), so I disabled in via BIOS.....and now the second screen works perfectly.

Obviously I would prefer not have disabled secureboot, does anyone have any idea what the proper fix for this would be?