use cu126 for 10 series and older GPUs

[w-e-w]

alternate PR for

• https://github.com/AUTOMATIC1111/stable-diffusion-webui/pull/17163
• https://github.com/AUTOMATIC1111/stable-diffusion-webui/pull/17171

apparently 10 series and older gpus don't work with cu128 10 series gpu have CUDA Compatibility of 7 and since GPU with Compatibility 7.2 is considered legacy by Nvidia I belive everything under 7.2 should use cu126

ref https://docs.nvidia.com/deeplearning/cudnn/backend/latest/reference/support-matrix.html https://developer.nvidia.com/cuda-gpus https://download.pytorch.org/whl/cu128 https://en.wikipedia.org/wiki/CUDA https://discuss.pytorch.org/t/uninstall-pytorch-completely-to-install-older-version/223551 https://dev-discuss.pytorch.org/t/cuda-toolkit-version-and-architecture-support-update-maxwell-and-pascal-architecture-support-removed-in-cuda-12-8-and-12-9-builds/3128

I don't fully understand the situation with older gpus from the information I can find it seems that they only deleted support on pytorch 2.8 and since we use 2.7 I'm not quite sure why it doesn't work with cu128

Checklist:

• [ ] I have read contributing wiki page
• [ ] I have performed a self-review of my own code
• [ ] My code follows the style guidelines
• [ ] My code passes tests

[w-e-w]

@kavyamali can you test this

should work but just to make sure

[kavyamali]

@kavyamali can you test this

should work but just to make sure

Testing right now, and it's currently downloading the correctly mentioned cu126. But it fails installation due to --no-cache-dir not being mentioned. If you want, I can edit my original code to default to cu126 for pascal as well. Or you can do so and add --no-cache-dir in your code as well. Thanks for your support. Everything else is perfect here.