经过两周的测试，仍未找到解决方案，我决定寻求帮助。我将总结我的情况。
imac 27" (from 2014) + Thunderbolt display 27" + Linux
当我过去使用 Ubuntu 14.04 LTS 时它运行良好，但经过一些更新后，第二台显示器无法工作。
因此，我决定清理我的电脑并安装全新的 Ubuntu 18.04 LTS。
在使用实时 USB 安装期间它可以工作，但重新启动后它就关闭了。
我确实需要第二个屏幕，因此我感谢专家的任何帮助。
一些说明：
显示器通过雷电线缆连接（像这样)，扬声器和 USB 均正常工作。只有屏幕关闭。
我尝试使用驱动程序：
nvidia-driver-390和nvidia-driver-340。xserver-xorg-video-nouveau我仍然有更新了 MacOS Mavericks 的分区，并且那里一切运行良好。
一些额外的信息
uname -a
Linux lali 4.18.0-25-generic #26~18.04.1-Ubuntu SMP Thu Jun 27 07:28:31 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
lspci
00:00.0 Host bridge: Intel Corporation 4th Gen Core Processor DRAM Controller (rev 06)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06)
00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05)
00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04)
00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5)
00:1c.2 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5)
00:1c.3 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #4 (rev d5)
00:1c.4 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #5 (rev d5)
00:1f.0 ISA bridge: Intel Corporation Z87 Express LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05)
00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05)
01:00.0 VGA compatible controller: NVIDIA Corporation GK104M [GeForce GTX 775M Mac Edition] (rev a1)
01:00.1 Audio device: NVIDIA Corporation GK104 HDMI Audio Controller (rev a1)
03:00.0 Network controller: Broadcom Inc. and subsidiaries BCM4360 802.11ac Wireless Network Adapter (rev 03)
04:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM57766 Gigabit Ethernet PCIe (rev 01)
04:00.1 SD Host controller: Broadcom Inc. and subsidiaries BCM57765/57785 SDXC/MMC Card Reader (rev 01)
05:00.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
06:00.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
06:03.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
06:04.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
06:05.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
06:06.0 PCI bridge: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
07:00.0 System peripheral: Intel Corporation DSL3510 Thunderbolt Controller [Cactus Ridge 4C 2012] (rev 03)
08:00.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
09:00.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
09:01.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
09:02.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
09:04.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
09:05.0 PCI bridge: Intel Corporation CV82524 Thunderbolt Controller [Light Ridge 4C 2010]
0a:00.0 PCI bridge: Pericom Semiconductor Device 400c (rev 02)
0b:03.0 PCI bridge: Pericom Semiconductor Device 400c (rev 02)
0c:00.0 USB controller: Pericom Semiconductor PI7C9X442SL USB OHCI Controller (rev 01)
0c:00.1 USB controller: Pericom Semiconductor PI7C9X442SL USB OHCI Controller (rev 01)
0c:00.2 USB controller: Pericom Semiconductor PI7C9X442SL USB EHCI Controller (rev 03)
0d:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM57761 Gigabit Ethernet PCIe (rev 10)
0e:00.0 FireWire (IEEE 1394): LSI Corporation FW643 [TrueFire] PCIe 1394b Controller (rev 08)
xrandr
Screen 0: minimum 8 x 8, current 2560 x 1440, maximum 16384 x 16384
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
2560x1440 59.95*+
1280x720 59.86
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
lsmod
Module Size Used by
rfcomm 77824 4
bnep 20480 2
nls_iso8859_1 16384 1
nvidia_uvm 757760 0
intel_rapl 20480 0
uvcvideo 94208 0
gpio_ich 16384 0
videobuf2_vmalloc 16384 1 uvcvideo
videobuf2_memops 16384 1 videobuf2_vmalloc
videobuf2_v4l2 24576 1 uvcvideo
nvidia_drm 40960 2
videobuf2_common 40960 2 videobuf2_v4l2,uvcvideo
btusb 45056 0
btrtl 16384 1 btusb
x86_pkg_temp_thermal 16384 0
btbcm 16384 1 btusb
applesmc 20480 0
input_polldev 16384 1 applesmc
videodev 188416 3 videobuf2_v4l2,uvcvideo,videobuf2_common
nvidia_modeset 1048576 11 nvidia_drm
intel_powerclamp 16384 0
nvidia 14376960 485 nvidia_uvm,nvidia_modeset
btintel 20480 1 btusb
bluetooth 552960 33 btrtl,btintel,btbcm,bnep,btusb,rfcomm
snd_hda_codec_hdmi 49152 1
ecdh_generic 24576 1 bluetooth
coretemp 16384 0
kvm_intel 208896 0
media 40960 2 videodev,uvcvideo
kvm 626688 1 kvm_intel
drm_kms_helper 172032 1 nvidia_drm
irqbypass 16384 1 kvm
snd_usb_audio 225280 5
snd_usbmidi_lib 32768 1 snd_usb_audio
drm 458752 5 drm_kms_helper,nvidia_drm
crct10dif_pclmul 16384 0
joydev 24576 0
crc32_pclmul 16384 0
snd_hda_codec_cirrus 20480 1
input_leds 16384 0
snd_hda_codec_generic 73728 1 snd_hda_codec_cirrus
ghash_clmulni_intel 16384 0
ipmi_devintf 20480 0
snd_hda_intel 40960 8
pcbc 16384 0
snd_seq_midi 16384 0
snd_seq_midi_event 16384 1 snd_seq_midi
wl 6447104 0
ipmi_msghandler 102400 2 ipmi_devintf,nvidia
snd_hda_codec 126976 4 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec_cirrus
fb_sys_fops 16384 1 drm_kms_helper
aesni_intel 200704 0
snd_hda_core 81920 5 snd_hda_codec_generic,snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec,snd_hda_codec_cirrus
aes_x86_64 20480 1 aesni_intel
syscopyarea 16384 1 drm_kms_helper
sysfillrect 16384 1 drm_kms_helper
sysimgblt 16384 1 drm_kms_helper
crypto_simd 16384 1 aesni_intel
snd_hwdep 20480 2 snd_usb_audio,snd_hda_codec
snd_rawmidi 32768 2 snd_seq_midi,snd_usbmidi_lib
snd_pcm 98304 6 snd_hda_codec_hdmi,snd_hda_intel,snd_usb_audio,snd_hda_codec,snd_hda_core
snd_seq 65536 2 snd_seq_midi,snd_seq_midi_event
snd_seq_device 16384 3 snd_seq,snd_seq_midi,snd_rawmidi
snd_timer 32768 2 snd_seq,snd_pcm
cfg80211 667648 1 wl
snd 81920 38 snd_hda_codec_generic,snd_seq,snd_seq_device,snd_hda_codec_hdmi,snd_hwdep,snd_hda_intel,snd_usb_audio,snd_usbmidi_lib,snd_hda_codec,snd_timer,snd_hda_codec_cirrus,snd_pcm,snd_rawmidi
cryptd 24576 3 crypto_simd,ghash_clmulni_intel,aesni_intel
acpi_als 16384 0
glue_helper 16384 1 aesni_intel
intel_cstate 20480 0
intel_rapl_perf 16384 0
mac_hid 16384 0
kfifo_buf 16384 1 acpi_als
mei_me 40960 0
mei 98304 1 mei_me
industrialio 69632 2 acpi_als,kfifo_buf
soundcore 16384 1 snd
lpc_ich 24576 0
apple_bl 16384 0
video 45056 0
sch_fq_codel 20480 4
parport_pc 36864 0
ppdev 20480 0
lp 20480 0
parport 49152 3 parport_pc,lp,ppdev
ip_tables 28672 0
x_tables 40960 1 ip_tables
autofs4 40960 2
hid_generic 16384 0
usbhid 49152 0
hid 122880 2 usbhid,hid_generic
firewire_ohci 40960 0
firewire_core 65536 1 firewire_ohci
thunderbolt 122880 0
crc_itu_t 16384 1 firewire_core
ahci 40960 3
tg3 167936 0
libahci 32768 1 ahci
sdhci_pci 36864 0
cqhci 24576 1 sdhci_pci
sdhci 49152 1 sdhci_pci