I successfully built PyTorch from source on Windows 11 using CUDA 12.9 for the RTX 5070. Still working through a small runtime issue, but the full build process is documented here on GitHub: [https://github.com/DMorford/TorchinDesiree]

EasydoesitDave: <h1><a name="p-473428-pytorch-rtx-5070-build-session-summary-1" class="anchor" href="#p-473428-pytorch-rtx-5070-build-session-summary-1"></a>=========================================<br>
PYTORCH RTX 5070 BUILD SESSION SUMMARY</h1>
<p>Date: July 24, 2025<br>
Machine: Desiree (i9-14900F, 32GB RAM, RTX 5070 12GB)<br>
CUDA Version: 12.9<br>
Build Status: COMPILATION SUCCESSFUL <img src="https://discuss.pytorch.org/images/emoji/apple/white_check_mark.png?v=14" title=":white_check_mark:" class="emoji" alt=":white_check_mark:" loading="lazy" width="20" height="20"></p>
<p>[DMorford/TorchinDesiree: <img src="https://discuss.pytorch.org/images/emoji/apple/fire.png?v=14" title=":fire:" class="emoji" alt=":fire:" loading="lazy" width="20" height="20"> Build logs, config notes, and experimental attempts for compiling PyTorch with CUDA support on the bleeding-edge RTX 5070 GPU (Desiree). Raw documentation of GPU pain, progress, and persistence in the quest for AI acceleration.]</p>
<p>(<a href="https://github.com/DMorford/TorchinDesiree" class="inline-onebox" rel="noopener nofollow ugc">GitHub - DMorford/TorchinDesiree: 🔥 Build logs, config notes, and experimental attempts for compiling PyTorch with CUDA support on the bleeding-edge RTX 5070 GPU (Desiree). Raw documentation of GPU pain, progress, and persistence in the quest for AI acceleration.</a>)</p>
<h1><a name="p-473428-what-we-accomplished-2" class="anchor" href="#p-473428-what-we-accomplished-2"></a>=========================================<br>
WHAT WE ACCOMPLISHED</h1>
<p><img src="https://discuss.pytorch.org/images/emoji/apple/white_check_mark.png?v=14" title=":white_check_mark:" class="emoji" alt=":white_check_mark:" loading="lazy" width="20" height="20"> MAJOR SUCCESS: PyTorch Build Completed</p>
<ul>
<li>Ninja build finished successfully</li>
<li>All CUDA 12.9 extensions compiled</li>
<li>RTX 5070 Blackwell architecture (sm_120) properly targeted</li>
<li>Build artifacts generated and installed</li>
</ul>
<p><img src="https://discuss.pytorch.org/images/emoji/apple/white_check_mark.png?v=14" title=":white_check_mark:" class="emoji" alt=":white_check_mark:" loading="lazy" width="20" height="20"> Environment Setup Perfected</p>
<ul>
<li>x64 Native Tools Command Prompt properly configured</li>
<li>Python 3.11.9 virtual environment working</li>
<li>CUDA 12.9 + RTX 5070 driver compatibility confirmed</li>
<li>All build dependencies installed and verified</li>
</ul>
<p><img src="https://discuss.pytorch.org/images/emoji/apple/white_check_mark.png?v=14" title=":white_check_mark:" class="emoji" alt=":white_check_mark:" loading="lazy" width="20" height="20"> Build Optimization</p>
<ul>
<li>18 parallel jobs utilized (perfect for i9-14900F)</li>
<li>Response files enabled to prevent Windows linking issues</li>
<li>Clean build environment with no conflicting artifacts</li>
</ul>
<h1><a name="p-473428-current-issue-3" class="anchor" href="#p-473428-current-issue-3"></a>=========================================<br>
CURRENT ISSUE</h1>
<p><img src="https://discuss.pytorch.org/images/emoji/apple/red_question_mark.png?v=14" title=":red_question_mark:" class="emoji" alt=":red_question_mark:" loading="lazy" width="20" height="20"> Import/Extension Linking Issue</p>
<ul>
<li>PyTorch builds successfully but import fails</li>
<li>C extensions not properly linked to Python environment</li>
<li>Common issue with Windows custom PyTorch builds</li>
<li>Error: “Failed to load PyTorch C extensions”</li>
</ul>

EasydoesitDave: <p>The build is now complete and running solid on both <strong>RTX 5070</strong> and <strong>RTX 5070 Ti</strong> with no issues on Windows 11. Just wanted to close the loop in case anyone else is looking for a ready-to-use setup.</p>
<aside class="onebox githubrepo" data-onebox-src="https://github.com/DMorford/TorchinDesiree">
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      <a href="https://github.com/DMorford/TorchinDesiree" target="_blank" rel="noopener nofollow ugc">github.com</a>
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  <h3><a href="https://github.com/DMorford/TorchinDesiree" target="_blank" rel="noopener nofollow ugc">GitHub - DMorford/TorchinDesiree: 🔥 Build logs, config notes, and experimental...</a></h3>

    <p><span class="github-repo-description">🔥 Build logs, config notes, and experimental attempts for compiling PyTorch with CUDA support on the bleeding-edge RTX 5070 GPU (Desiree). Raw documentation of GPU pain, progress, and persistence in the quest for AI acceleration.</span></p>
</div>

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<p><strong>Hardware:</strong> RTX 5070 12GB &amp; RTX 5070Ti 16GB (Blackwell sm_120)</p>
<ul>
<li>
<p><strong>CUDA:</strong> 12.8.0 (Working) vs 12.9.0 (Failed)</p>
</li>
<li>
<p><strong>PyTorch:</strong> 2.9.0.dev20250803+cu128 (Nightly)</p>
</li>
<li>
<p><strong>AI Assistant:</strong> Claude Code by Anthropic</p>
</li>
<li>
<p><strong>OS:</strong> Windows 11 Professional</p>
</li>
<li>
<p><strong>IDE:</strong> Visual Studio 2022 Community</p>
</li>
</ul>