已安装CUDA与PyTorch，torch.cuda.is_available()仍返回false求助

环境信息 #

• 显卡：NVIDIA GeForce GTX 1650 Ti（已确认兼容CUDA 12.1）
• nvidia-smi输出：

+---------------------------------------------------------------------------------------+
| NVIDIA-SMI 531.14                 Driver Version: 531.14       CUDA Version: 12.1     |
|-----------------------------------------+----------------------+----------------------+
| GPU  Name                      TCC/WDDM | Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf            Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                                         |                      |               MIG M. |
|=========================================+======================+======================|
|   0  NVIDIA GeForce GTX 1650 Ti    WDDM | 00000000:01:00.0 Off |                  N/A |
| N/A   37C    P8                4W /  N/A|      0MiB /  4096MiB |      0%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+

+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|  No running processes found                                                           |
+---------------------------------------------------------------------------------------+

安装命令 #

使用以下conda命令安装PyTorch：

conda install pytorch torchvision torchaudio pytorch-cuda=12.1 -c pytorch-nightly -c nvidia

问题现象 #

执行torch.cuda.is_available()返回false

补充细节 #

nvcc --version输出 #

nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2023 NVIDIA Corporation
Built on Mon_Apr__3_17:36:15_Pacific_Daylight_Time_2023
Cuda compilation tools, release 12.1, V12.1.105
Build cuda_12.1.r12.1/compiler.32688072_0

python -m torch.utils.collect_env关键输出 #

PyTorch version: 2.1.0.dev20230608
Is debug build: False
CUDA used to build PyTorch: Could not collect
ROCM used to build PyTorch: N/A

[...]

Is CUDA available: False
CUDA runtime version: 12.1.105
CUDA_MODULE_LOADING set to: N/A
GPU models and configuration: GPU 0: NVIDIA GeForce GTX 1650 Ti
Nvidia driver version: 531.14

[...]

[conda] pytorch                   2.1.0.dev20230608    py3.10_cpu_0    pytorch-nightly
[conda] pytorch-cuda              12.1                 hde6ce7c_5    pytorch-nightly
[conda] pytorch-mutex             1.0                         cpu    pytorch-nightly
[conda] torchaudio                2.1.0.dev20230608       py310_cpu    pytorch-nightly
[conda] torchvision               0.16.0.dev20230608       py310_cpu    pytorch-nightly

解决方法 #

从collect_env输出能明显看到，你安装的是CPU版本的PyTorch（包后缀为py3.10_cpu_0），这就是CUDA无法被识别的核心原因。按以下步骤修复：

1. 卸载当前的CPU版PyTorch套件：

conda uninstall pytorch torchvision torchaudio pytorch-cuda pytorch-mutex

2. 重新安装支持CUDA 12.1的PyTorch版本：

   • 若不需要nightly预览版，优先用稳定版命令：

   conda install pytorch torchvision torchaudio pytorch-cuda=12.1 -c pytorch -c nvidia
   

   • 若必须用nightly版，执行命令后留意conda的输出日志，确保安装的包后缀是cuda121而非cpu：

   conda install pytorch torchvision torchaudio pytorch-cuda=12.1 -c pytorch-nightly -c nvidia
   

3. 安装完成后验证：

   • 打开Python终端，执行import torch; print(torch.cuda.is_available())，返回True则说明CUDA识别正常。
   • 执行torch.version.cuda，确认输出为12.1。

内容的提问来源于stack exchange，提问作者PhoenXHO