Can the RTX 3070 8 GB run LTX-2 (19B)?
Not entirely. Even Q4_K_M is 9.6 GB over 8 GB, so ComfyUI keeps part of it in system RAM.
The smallest sensible file, Q4_K_M (12.8 GB), needs about 17.6 GB - 9.6 GB more than RTX 3070 8 GB 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.
01With more VRAM
With 32 GB you could run LTX-2 at 8-bit or better (Q8_0, 20.4 GB) with no offloading: for example on the RTX 5090 32 GB.
What changes from the RTX 3070 8 GB to the RTX 5060 Ti 16 GB → · What changes from the RTX 3070 8 GB to the RTX 3090 24 GB →
02Every LTX-2 file on 8 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit GGUF · unsloth | 37.8 GB | 42.6 GB | 34.6 GB too big | the original weights | Hugging Face → |
| Q8_0 GGUF · unsloth | 20.4 GB | 25.2 GB | 17.2 GB too big | practically identical to the original | Hugging Face → |
| Q6_K GGUF · unsloth | 16.0 GB | 20.8 GB | 12.8 GB too big | very close to the original | Hugging Face → |
| Q5_K_M GGUF · unsloth | 14.3 GB | 19.1 GB | 11.1 GB too big | close; small differences in fine detail | Hugging Face → |
| Q4_K_M ← GGUF · unsloth | 12.8 GB | 17.6 GB | 9.6 GB too big | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · unsloth | 10.1 GB | 14.9 GB | 6.9 GB too big | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · unsloth | 8.1 GB | 12.9 GB | 4.9 GB too big | heavy loss; a last resort | Hugging Face → |
“Needed” adds 4 GB of working memory for LTX-2 and a 0.8 GB reserve. Sizes 2026-10-01.
03What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | ltx-2-19b-dev-Q4_K_M.gguf Q4_K_M · unsloth/LTX-2-GGUF | models/unet | 12.8 GB | Download → |
| Text encoder | gemma_3_12B_it_fp8_scaled.safetensors Gemma 3 12B FP8 (scaled) · Comfy-Org/ltx-2 | models/text_encoders | 13.2 GB | Download → |
| VAE | ltx-2-19b-dev_video_vae.safetensors LTX-2 video VAE · unsloth/LTX-2-GGUF | models/vae | 2.4 GB | Download → |
| Also needed | ltx-2-19b-dev_audio_vae.safetensors LTX-2 audio VAE · unsloth/LTX-2-GGUF | models/vae | 0.2 GB | Download → |
| Also needed | ltx-2-19b-dev_embeddings_connectors.safetensors LTX-2 text embeddings connectors (projection) · unsloth/LTX-2-GGUF | models/text_encoders | 2.9 GB | Download → |
| Total download · keep about the same free on disk | 31.6 GB | |||
Alternatives: Gemma 3 12B FP4 mixed (9.4 GB); Gemma 3 12B BF16 (24.4 GB). FP4 files are listed only as alternatives unless the GPU is an RTX 50 (Blackwell). Only for some workflows: LTX-2 spatial upscaler x2 (1.0 GB, official two-stage template). Sizes from Hugging Face, 2026-10-01.
System RAM: 48 GB or more. These files take about 31.6 GB of RAM while loaded, 37.6 GB with Windows and ComfyUI. What happens with less. calculated
04The text encoder
At 9.4 GB even the smallest Gemma 3 12B file is too big for 8 GB, so it runs from system RAM. That slows down reading the prompt, not the picture. Sizes: 16-bit 24.4 GB, FP8 13.2 GB, FP4 mixed 9.4 GB. Why the encoder does not count against VRAM →
05Measured and reported results
Nobody has sent measured numbers for this pair yet. If you run LTX-2 on a RTX 3070 8 GB, send your time per image and peak VRAM and it will appear here, credited.
06About the RTX 3070 8 GB
The RTX 3070 8 GB (Ampere) has no FP8 compute. FP8 files still load and save memory, but ComfyUI converts them back before the maths, so there is no speed gain - Q8_0 GGUF is the closer-to-original 8-bit choice. ComfyUI can compute INT8 files natively on NVIDIA, which is worth a try where a model offers one.
8 GB GDDR6 · 256-bit · 448 GB/s · Ampere. Everything that runs on it →
07Questions
How much VRAM does LTX-2 need?
Around 12.9 GB with the smallest file (Q2_K) and 25.2 GB with an 8-bit file (Q8_0). The full 16-bit file needs about 42.6 GB.
Which LTX-2 file should I download for the RTX 3070 8 GB?
Q4_K_M (12.8 GB) from unsloth/LTX-2-GGUF. Load it with Unet Loader (GGUF) from the ComfyUI-GGUF node pack.
How much do I need to download for LTX-2 on the RTX 3070 8 GB?
31.6 GB: ltx-2-19b-dev-Q4_K_M.gguf, gemma_3_12B_it_fp8_scaled.safetensors, ltx-2-19b-dev_video_vae.safetensors, ltx-2-19b-dev_audio_vae.safetensors, ltx-2-19b-dev_embeddings_connectors.safetensors.