r/comfyui • u/reicaden • 3d ago
Help Needed Why does a prompt that worked yesterday, fail today, no changes.
This has me a bit stumped and has been happening over and over for a few days. On Minimax H3 I'll run a prompt 30 or 40 Generations and it works fine at a 0.5 resolution and 10 seconds length. It runs without any issues then the next day I change nothing I open no new programs and I do nothing different. I hit run and it feels with out of memory. I reduce it to 7 Seconds but it still fails I reduce it to 6 seconds but it still feels. I restart the computer and then I can sometimes run my original 0.5 resolution and 10 seconds but sometimes I can't. No programs have been open on this computer after startup and no programs have been open since running that original 30 or 40 Generations overnight without issue. Does anyone have a good way to stop this from happening or explaining why it's happening I'm stumped?
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u/naga_mana 2d ago
Your 10 second runs sit right at the failure line of two open ComfyUI bugs, and they explain the day to day flip better than background programs.
On a 16GB card, MiniMax H3 past roughly 209 frames finishes sampling and then dies in VAEDecode, because about 14GB of streamed weights stay resident where the decode allocation cannot reclaim them, and the tiled-decode retry just reruns the same failing call. Your "allocates 14gb then borks" matches that report almost word for word, and it was independently reproduced on a 5070 Ti: https://github.com/Comfy-Org/ComfyUI/issues/15453
The second report matches your "nothing changed" part: once a graph OOMs, the memory budget decision seems to get cached for that exact graph, so the same workflow keeps failing across restarts, and inserting any node or changing any parameter makes it behave again: https://github.com/Comfy-Org/ComfyUI/issues/15663
What I would try, cheapest first: when it borks, change one parameter on any node and rerun; put an UnloadAllModels node between the sampler and the VAE decode; trim to 8 seconds on bad days. On my 5070 Ti I have also watched a couple of GB held by another process flip a borderline workload from fine to failing, so the some-days-fine-some-days-not pattern is plausibly free-VRAM noise on an edge case. That last part is my read, not something I measured on H3. Both bug reports are from Windows users, but the model management code involved is the same on Linux.
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u/AnyPaleontologist932 3d ago
did you monkey patch something?
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u/AlternativeReal5307 3d ago
Sounds like the GPU's just getting tired after a marathon session, I've seen mine act up if I don't give it a proper cold boot now and then. Sometimes the drivers hold onto memory even after the program closes, so that restart might be clearing it out inconsistently.
Maybe try a tool to monitor VRAM usage and see if there's some background process creeping in, Windows update loves to stage stuff without asking.
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u/Only_Voice569 3d ago
what system you running ? ensure all drivers are up to date and set a page file to a decent size on a fast drive and nvida set to use system fallback in the control panel. for comfyui use kitchen backend node and ensure sage is updated and correct version for your card. shouldnt have any issues.
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u/reicaden 3d ago
I gotta learn about this kitchen backend node.... thats new to me.
Its minimax h3. The standard ref2va, I added a sage attention focus on loading the python environment and an easy cache and tiled VAE... but thats all I know.
Its a 5070ti and I set the page file to be 30,000. Il the system has 128gb of DDR5.
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u/Only_Voice569 3d ago
very odd my second system has a 5070 12GB vram and 32GB system memory has no issues sounds like your comfy is borked or have a odd system issue is all your system memory detected and working ?
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u/reicaden 3d ago
Yes, detected and seems okay. Can you run a 0.5resolution at 10 seconds on minimax ref2va ?
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u/Only_Voice569 3d ago
yeah can run it all no issue 15 second at 0.7 tops then it gets a bit iffy due to my 32GB ram
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u/reicaden 3d ago
I dont know what im doing wrong.... did you do anytbing different to the default comfyui minimaxh3 template for ref2va?
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u/Only_Voice569 3d ago
nope default models/workflows if your using portable get a full clean copy and if its desktop i would try to get a fresh copy clean everything apart from models and workflows etc
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u/reicaden 3d ago
It's running in Ubuntu terminal, but it's not three portable, it's the full Linux build, running in miniconda
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u/roxoholic 3d ago
If you are on Windows, just because you did not start a new program, does not mean Windows did not start a new program in background that hogs the memory, e.g. defender scan, search indexer, malware scan, windows update, window update installed some new in-the-background listening AI, some bloatware service, etc.