安装NVIDIA驱动后Ubuntu陷入登录循环问题求助（GTX 950M）

Hey there, I totally get how frustrating this login loop is—especially when you’ve already tried all the standard fixes. Let’s walk through targeted solutions tailored to your GTX 950M and dual-boot setup:

Step 1: Escape the Login Loop via TTY Mode #

First, get out of the stuck login screen by pressing Ctrl + Alt + F2 (or any F key from F3 to F6). You’ll see a text terminal—log in with your username and password to proceed.

Step 2: Purge All Faulty NVIDIA Driver Traces #

Start fresh by removing every trace of the current drivers that might be causing conflicts:

sudo apt-get purge nvidia*
sudo apt-get autoremove
sudo apt-get autoclean

Step 3: Install a Stable Driver for GTX 950M #

The GTX 950M uses the Maxwell architecture, and newer drivers often clash with older Ubuntu versions. Stick with the 390.x series—it’s reliably stable for this GPU:

• For Ubuntu 16.04:

  sudo add-apt-repository ppa:graphics-drivers/ppa
  sudo apt-get update
  sudo apt-get install nvidia-390
  

• For Ubuntu 14.04:
  The graphics-drivers PPA has limited support here, so try direct installation:

  sudo apt-get install nvidia-390
  

Step 4: Fix Dual-Boot Hardware Lock (Windows Fast Startup) #

Windows 8.1’s Fast Startup locks hardware resources (including your GPU) even when "shut down," which breaks Ubuntu’s access to the graphics card:

1. Reboot into Windows 8.1
2. Navigate to Control Panel → Power Options → Choose what the power buttons do
3. Click Change settings that are currently unavailable
4. Uncheck Enable fast startup (recommended)
5. Shut down Windows completely (no hibernation/sleep) and boot back into Ubuntu

Step 5: Troubleshoot the Display Manager (LightDM) #

If the login loop persists, reset or restart LightDM:

sudo service lightdm restart

If that fails, reconfigure LightDM to ensure it uses the correct driver:

sudo dpkg-reconfigure lightdm

When prompted, select lightdm as your default display manager.

Quick Checks If Issues Remain #

• Run nvidia-smi in TTY mode—if it returns a valid GPU info, the driver is installed correctly. If not, repeat the purge and install steps.
• Avoid 4xx+ series NVIDIA drivers on Ubuntu 14.04/16.04 for your GPU—they’re optimized for newer hardware and often cause stability problems.

内容的提问来源于stack exchange，提问作者Mariem Slim