Can the RTX 5090 32 GB run LTX-2 (19B)?
Download Q8_0 (20.4 GB). With the model's working memory it needs about 25.2 GB, leaving 6.8 GB spare on 32 GB. Quality: practically identical to the original.
01What to download
| Part | File | Folder | Size | |
|---|---|---|---|---|
| Model | ltx-2-19b-dev-Q8_0.gguf Q8_0 · unsloth/LTX-2-GGUF | models/unet | 20.4 GB | Download → |
| Text encoder | gemma_3_12B_it_fp4_mixed.safetensors Gemma 3 12B FP4 mixed · Comfy-Org/ltx-2 | models/text_encoders | 9.4 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 | 35.4 GB | |||
Alternatives: Gemma 3 12B FP8 (scaled) (13.2 GB); Gemma 3 12B BF16 (24.4 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. Only for some workflows: LTX-2 spatial upscaler x2 (1.0 GB, official two-stage template). 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: 48 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 35.4 GB, plus roughly 6 GB for Windows, ComfyUI and a browser: 41.4 GB in total. With less RAM it still runs, but Windows starts swapping to disk and loading gets very slow. calculated
02Every LTX-2 file on 32 GB
| File | Size | Needed | On this card | Quality | Download |
|---|---|---|---|---|---|
| 16-bit GGUF · unsloth | 37.8 GB | 42.6 GB | 10.6 GB too big | the original weights | Hugging Face → |
| Q8_0 ← GGUF · unsloth | 20.4 GB | 25.2 GB | fits · 6.8 GB spare | practically identical to the original | Hugging Face → |
| Q6_K GGUF · unsloth | 16.0 GB | 20.8 GB | fits · 11.2 GB spare | very close to the original | Hugging Face → |
| Q5_K_M GGUF · unsloth | 14.3 GB | 19.1 GB | fits · 12.9 GB spare | close; small differences in fine detail | Hugging Face → |
| Q4_K_M GGUF · unsloth | 12.8 GB | 17.6 GB | fits · 14.4 GB spare | good; some loss in fine detail and text | Hugging Face → |
| Q3_K_M GGUF · unsloth | 10.1 GB | 14.9 GB | fits · 17.1 GB spare | noticeable loss of detail | Hugging Face → |
| Q2_K GGUF · unsloth | 8.1 GB | 12.9 GB | fits · 19.1 GB spare | heavy loss; a last resort | Hugging Face → |
Sizes from the Hugging Face file listing, read 2026-09-25. “Needed” = file + 4 GB working memory for this model + 0.8 GB kept free for the system.
03The text encoder
Gemma 3 12B: 24.4 GB as 16-bit, 13.2 GB as FP8, 9.4 GB as FP4 mixed. 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 32 GB the FP8 encoder fits on its own, so prompt encoding stays fast.
04About this GPU
The RTX 5090 32 GB is a Blackwell GPU with FP8 and FP4 hardware: ComfyUI computes Comfy-Org's FP8 files natively here, and NVFP4 files (where a model offers them) are faster still.
RTX 5090 32 GB: 32 GB GDDR7 · 512-bit · 1792 GB/s · Blackwell. Everything that runs on the RTX 5090 32 GB →
05What more VRAM would change
Nothing to gain for this model: the RTX 5090 32 GB already runs a top-quality file entirely in VRAM. More memory would only help with bigger images, longer clips or several models at once.
06Measured and reported results
| Label | Setup | Result | Peak VRAM | Date | Source |
|---|---|---|---|---|---|
| reported | LTX-2 19B NVFP4 · 720p “generating 143 frames at 720p takes about 66 seconds end‑to‑end in ComfyUI” Issue says this is ~30-40% slower than NVIDIA's expected 40-45 s; steps not stated | 66 s / clip (143 frames) | — | 2026-01-08 | github.com → |
Reported results are other people's numbers, copied as published, with a link. Settings, drivers and ComfyUI versions differ, so compare them with care. Send yours.
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), counting working memory and a small system reserve. The full 16-bit file needs about 42.6 GB.
Which LTX-2 file should I download for the RTX 5090 32 GB?
Q8_0 (20.4 GB) from unsloth/LTX-2-GGUF. Load it with Unet Loader (GGUF) from the ComfyUI-GGUF node pack.
Is FP8 faster than GGUF on the RTX 5090 32 GB?
It can be. This GPU has FP8 hardware, and ComfyUI computes FP8 natively for files made for it (Comfy-Org's fp8_scaled files), or for any FP8 file with the --fast fp8_matrix_mult option. GGUF files are unpacked on the fly, which costs some speed.
How much do I need to download for LTX-2 on the RTX 5090 32 GB?
About 35.4 GB for the model file, text encoder and VAE listed on this page, and the same again free on disk. With a 32 GB card, 48 GB of system RAM or more is recommended.