Hy4 Preview has 780.0B parameters (49B active per token). In BF16 its weights alone take 1434 GiB; quantized to 4-bit, about 433 GiB. Each 32K-token request adds 2.83 GiB of KV cache. Cheapest way to run it today: 7 × NVIDIA A100 80GB at $4.41 per hour. It calls tools and lets you set its reasoning effort.
Read every day from Hugging Face. Split files are added together; vision projectors are left out.
How many GPUs to run Hy4 Preview
Fewest GPUs that fit the weights plus one 8K-token request. Data-center GPUs use vLLM (90% of memory usable), the others llama.cpp. Several GPUs split the model with tensor or pipeline parallelism.
GPU
FP8 (native)
BF16 / FP16
8-bit
4-bit
GeForce RTX 4090 24 GB
Not on this GPU
96 (several machines)
48 (several machines)
24 (several machines)
GeForce RTX 5090 32 GB
Not on this GPU
64 (several machines)
32 (several machines)
16 (several machines)
RTX PRO 6000 Blackwell 96 GB
Not on this GPU
16 (several machines)
8
5
Mac M5 Max 128 GB 96 GB usable
Not on this GPU
16 (several machines)
8
5
Ryzen AI Max+ 395 128 GB 96 GB usable
Not on this GPU
16 (several machines)
8
5
DGX Spark (GB10) 128 GB
Not on this GPU
16 (several machines)
6
4
NVIDIA H100 80 GB
16 (several servers)
24 (several servers)
16 (several servers)
7
NVIDIA H200 141 GB
7
16 (several servers)
6
4
NVIDIA B200 (HGX) 180 GB
5
16 (several servers)
5
3
8-bit: FP8 with vLLM (INT8 on GPUs without FP8), Q8_0 with llama.cpp. 4-bit: AWQ / GPTQ with vLLM, Q4_K_M with llama.cpp, both counted at the Q4_K_M size. Not on this GPU: the official FP8 weights do not run there (llama.cpp needs a GGUF version, and vLLM needs a GPU with FP8 support).
Cheapest way to run Hy4 Preview today
For each GPU: the fewest cards that fit Hy4 Preview with one 8K-token request, the most faithful weight format at that count, and the cheapest on-demand price (2026-10-30).
On-demand prices from AWS, Google Cloud, Azure, RunPod, Vast.ai, Oracle Cloud, OVHcloud, Scaleway, Verda, Akash and UpCloud, checked every hour. Serving many users needs more KV cache, so more memory: size it in the calculator. Some links are affiliate links: StudioTV may earn a commission, at no extra cost to you.
vLLM and SGLang apply these defaults unless a request sets its own. With llama.cpp, pass them yourself: --temp 0.9 --top-p 1
Reasoning. Adjustable reasoning effort. Reasoning tokens take context and KV cache like any other token: leave room for them.
KV cache: how memory grows with context
Architecture: MoE 256 experts + 1 shared · gated DSA: MLA (512 + 64 latent) on 78 layers · sparse-attention indexer keys on 21. Its cache stays compact because MLA stores one compressed latent per token and layer instead of full keys and values. Only 49B parameters are active per token, but all 780B must sit in memory: VRAM depends on the total, speed on the active part.
Context per request
BF16 cache
FP8 cache
8K tokens
0.71 GiB
0.41 GiB
32K tokens
2.83 GiB
1.65 GiB
128K tokens
11.3 GiB
6.58 GiB
1M tokens
90.5 GiB
52.7 GiB
Hy4 Preview VRAM FAQ
How much VRAM does Hy4 Preview need?
In BF16 the weights alone take 1434 GiB (1540 GB). In FP8 that is 718 GiB, and about 433 GiB with 4-bit quantization (Q4_K_M); the official FP8 checkpoint is 748 GiB. Each request then adds KV cache: 0.71 GiB at 8K tokens and 2.83 GiB at 32K (BF16 cache).
Can Hy4 Preview run on a single RTX 4090 (24 GB)?
No. Even in 4-bit it needs 24 RTX 4090s, spread over several machines. In 4-bit it needs 7 H100 GPUs.
Can Hy4 Preview run on an RTX 5090 (32 GB)?
No. Even in 4-bit it needs 16 RTX 5090s, spread over several machines.
Can Hy4 Preview run on a Mac?
No single Mac holds it, even in 4-bit: it needs 434 GiB with an 8K-token context, and the largest Mac (512 GB) gives its GPU about 384 GB.
Can Hy4 Preview run on a DGX Spark or a Ryzen AI Max+ 395 (128 GB)?
No. Even in 4-bit it needs 4 DGX Spark units or 5 Ryzen AI Max+ 395 machines (128 GB), linked over the network.
What is the cheapest way to run Hy4 Preview?
On 2026-10-30, the cheapest on-demand setup is 7 × NVIDIA A100 80GB with 4-bit weights on Vast.ai, at $4.41 per hour (about $3,219.30 per month). Next: 5 × RTX PRO 6000 Blackwell (96 GB) with Q4_K_M weights on Vast.ai, at $6.67 per hour. Sized for one 8K-token request; prices are checked every hour.
How many H100 GPUs does Hy4 Preview need?
With one request and an 8K-token context: 24 in BF16, 16 in FP8 and 7 in 4-bit (vLLM, 90% of memory usable). Above 8 GPUs, that means several servers. Serving many users at once needs more memory for their KV caches: the calculator sizes that for you.
Does Hy4 Preview support tool calling?
Yes, Hy4 Preview supports tool (function) calling: it can ask your application to run a function and use the result.
Does Hy4 Preview have a thinking mode?
Adjustable reasoning effort. Reasoning tokens count toward the context and the KV cache.
What temperature should I use with Hy4 Preview?
The official defaults are temperature 0.9, top-p 1.
Hy4 Preview VRAM badge
For a model card or a README: the 4-bit size and the smallest GPU it fits on, linked to this page. Data as JSON: /api/models/hy4-preview.json.
Estimates, not guarantees: computed from the official config.json with the same engine as the LLM VRAM Calculator. Real usage depends on your engine version and settings.