<h2 id="blackwell-attention-fix-(rtx-50xx)">Blackwell Attention Fix (RTX 50xx)</h2><h3 id="overview">Overview</h3>Runtime ComfyUI node that prevents the common xformers crash on NVIDIA Blackwell GPUs (RTX 5090 / 5080 / 5070):the=is prevents you from having to disable xfromers, which may slow your machine down. If you prefer, add his to your .bat file: --disable-xformers --use-pytorch-cross-attentionGitHub Repo: <a target="_blank" rel="ugc" href="https://github.com/lonecatone23/comfyUI-BlackwellAttentionFix">https://github.com/lonecatone23/comfyUI-BlackwellAttentionFix</a>NotImplementedError: No operator found for <code>memory_efficient_attention_forward</code>… requires device with capability ≤ (9, 0) but your GPU has capability (12, 0) (too new)It works by redirecting ComfyUI’s attention entry points to the built-in <code>attention_pytorch</code> (SDPA) implementation, which is fully compatible with compute capability 12.0.<h3 id="modes">Modes</h3>bypass (default) : No-op. Model passes through unchanged. Safe for any GPU and shared workflows.pytorch :Forces native PyTorch attention. Only applies the change when a Blackwell GPU is detected.<h3 id="usage">Usage</h3>- Insert the node immediately after any model / UNET / Krea2 loader and before samplers or attention-heavy custom nodes.- On RTX 50-series + Krea2 (or any model that triggers the xformers error) → set mode = pytorch.- On all other systems or shared workflows → leave mode = bypass.The node can stay permanently in a workflow; with <code>bypass</code> it never interferes with xformers, SageAttention, or other people’s setups.What it patches- <code>comfy.ldm.modules.attention.optimized_attention</code>- <code>optimized_attention_masked</code>- <code>attention_xformers</code>- Direct imports captured at load time (notably <code>comfy.ldm.krea2.model</code>)<h3 id="compatibility">Compatibility</h3>- Works with Krea2 / krea2edit, Flux, SDXL, SD1.5, Wan, LTX and most other models that go through ComfyUI’s standard attention path.- Does not require launch flags <code>--disable-xformers</code>, etc.).- Does not uninstall or break xformers; it only redirects the active functions for the current process when enabled.<h3 id="limitations">Limitations</h3>- VAE may still log “Using xformers attention” — this is harmless and separate from the diffusion attention path that was crashing.- Performance is native PyTorch SDPA (usually close to xformers on Blackwell). SageAttention is not used by this node.- Extremely rare custom nodes that hard-code their own xformers calls are not covered.<h3 id="license-status">License / Status</h3>Community utility node. No external dependencies beyond ComfyUI + PyTorch.<hr />Instagram: <a target="_blank" rel="ugc" href="https://www.instagram.com/synth.studio.models/">https://www.instagram.com/synth.studio.models/</a>Buy me a☕ <a target="_blank" rel="ugc" href="https://ko-fi.com/lonecatone">https://ko-fi.com/lonecatone</a>This represents several hours of work that I give away for free. If you enjoy it, Please make sure to 👍like and post to my workflows. That is how you support me!!! Also, feel free to ⚡tip 😉

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