LTX-Video 13B (0.9.8) on 6 GB of VRAM
The smallest sensible file, Q4_K_M (8.8 GB), needs about 13.1 GB — 7.1 GB more than 6 GB GPU has. ComfyUI can still run it by streaming part of the model from system RAM. How much slower that is depends on your ComfyUI version, the file format and the PCIe link — see the note below.
Worth trying on NVIDIA GPUs: with an up-to-date ComfyUI, Dynamic VRAM (on by default for NVIDIA since March 2026) streams whatever does not fit from system RAM, and ComfyUI's own start-up message recommends native FP8/INT8 files over GGUF, saying they “will be faster even if they are larger than your memory”. So before settling for a heavily compressed GGUF, try the native FP8 file (15.7 GB). The file recommended above is the best one that fits entirely — the safe choice on older ComfyUI versions, AMD and Intel. Comfy blog: Dynamic VRAM →
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | LTXV-13B-0.9.8-dev-Q4_K_M.gguf Q4_K_M · QuantStack/LTXV-13B-0.9.8-dev-GGUF | models/unet | 8.8 GB | Download → |
| Text encoder | t5xxl_fp8_e4m3fn_scaled.safetensors T5-XXL FP8 (scaled) · comfyanonymous/flux_text_encoders | models/text_encoders | 5.2 GB | Download → |
| VAE | LTXV-13B-0.9.8-dev-VAE.safetensors LTXV 13B 0.9.8 VAE (standalone, QuantStack) · QuantStack/LTXV-13B-0.9.8-dev-GGUF | models/vae | 2.5 GB | Download → |
| Total download · keep about the same free on disk | 16.5 GB | |||
Alternatives: T5-XXL FP16 (9.8 GB). The 16-bit text encoder is a little more faithful; the smaller one is chosen here because it loads faster and needs less RAM. Sizes read from Hugging Face (2026-09-25). “Download” links start the file directly; the file name links are the same files the official ComfyUI workflows use.
System RAM: 32 GB or more. ComfyUI keeps the model file, the text encoder and the VAE in system RAM and moves them to the GPU as needed. With this set of files that is about 16.5 GB, plus roughly 6 GB for Windows, ComfyUI and a browser: 22.5 GB in total. With less RAM it still runs, but Windows starts swapping to disk and loading gets very slow. calculated
02Every file, on 6 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit SAFETENSORS · Lightricks | 28.6 GB | 32.9 GB | 26.9 GB too big | the original weights | Hugging Face → |
| Q8_0 GGUF · QuantStack | 14.0 GB | 18.3 GB | 12.3 GB too big | practically identical to the original | Hugging Face → |
| FP8 SAFETENSORS · Lightricks | 15.7 GB | 20.0 GB | 14.0 GB too big | practically identical to the original | Hugging Face → |
| Q6_K GGUF · QuantStack | 10.9 GB | 15.2 GB | 9.2 GB too big | very close to the original | Hugging Face → |
| Q5_K_M GGUF · QuantStack | 9.8 GB | 14.1 GB | 8.1 GB too big | close; small differences in fine detail | Hugging Face → |
| Q4_K_M ← GGUF · QuantStack | 8.8 GB | 13.1 GB | 7.1 GB too big | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · QuantStack | 6.5 GB | 10.8 GB | 4.8 GB too big | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · QuantStack | 4.7 GB | 9.0 GB | 3.0 GB too big | heavy loss; a last resort | Hugging Face → |
Sizes from the Hugging Face file listing, read 2026-09-25. “Needed” = file + 3.5 GB working memory for this model + 0.8 GB kept free for the system.
03The text encoder
T5-XXL: 9.8 GB as 16-bit, 4.9 GB as FP8, 2.9 GB as GGUF Q4_K_M (plus CLIP-L (0.25 GB)). ComfyUI encodes the prompt first and can push the encoder out of VRAM before sampling, so it does not have to fit together with the model. On 6 GB the FP8 encoder fits on its own, so prompt encoding stays fast.