Step 3.5 Flash Base — Hardware Requirements & GPU Compatibility
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Step 3.5 Flash Base is a 197.8B-parameter open language model from stepfun-ai. It supports a context window of up to 32,768 tokens. At IQ4_XS it needs about 116.93 GB of VRAM — see which GPUs and Macs can run it below.
685 downloads
78 likesSpecifications
- Publisher
- stepfun-ai
- Parameters
- 197.8B
- Architecture
- Step3p5ForCausalLM
- Context Length
- 32,768 tokens
- Vocabulary Size
- 128,815
- Release Date
- 2026-03-09
- License
- Apache 2.0
Get Started
HuggingFace
How Much VRAM Does Step 3.5 Flash Base Need?
Select a quantization to see compatible GPUs below.
| Quantization | Bits | VRAM | + Context | File Size | Quality |
|---|---|---|---|---|---|
| IQ4_XS | 4.30 | 116.9 GB | — | 106.30 GB | Importance-weighted 4-bit, compact |
Which GPUs Can Run Step 3.5 Flash Base?
IQ4_XS · 116.9 GBStep 3.5 Flash Base (IQ4_XS) requires 116.9 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 153+ GB is recommended. No single GPU has enough memory — multi-GPU or cluster setups are needed.
Which Devices Can Run Step 3.5 Flash Base?
IQ4_XS · 116.9 GB5 devices with unified memory can run Step 3.5 Flash Base, including NVIDIA DGX H100, NVIDIA DGX A100 640GB, Mac Studio M4 Max (128 GB).
Runs great
— Plenty of headroom
Decent
— Enough memory, may be tightRelated Models
Frequently Asked Questions
- How much VRAM does Step 3.5 Flash Base need?
Step 3.5 Flash Base requires 116.9 GB of VRAM at IQ4_XS.
VRAM = Weights + KV Cache + Overhead
Weights = 197.8B × 4.3 bits ÷ 8 = 106.3 GB
KV Cache + Overhead ≈ 10.6 GB (at 2K context + ~0.3 GB framework)
VRAM usage by quantization
IQ4_XS116.9 GB- Can NVIDIA GeForce RTX 5090 run Step 3.5 Flash Base?
No — Step 3.5 Flash Base requires at least 116.9 GB at IQ4_XS, which exceeds the NVIDIA GeForce RTX 5090's 32 GB of VRAM.
- Can I run Step 3.5 Flash Base on a Mac?
Step 3.5 Flash Base requires at least 116.9 GB at IQ4_XS, which exceeds the unified memory of most consumer Macs. You would need a Mac Studio or Mac Pro with a high-memory configuration.
- Can I run Step 3.5 Flash Base locally?
Yes — Step 3.5 Flash Base can run locally on consumer hardware. At IQ4_XS quantization it needs 116.9 GB of VRAM. Popular tools include Ollama, LM Studio, and llama.cpp.
- How fast is Step 3.5 Flash Base?
At IQ4_XS, Step 3.5 Flash Base can reach ~25 tok/s on AMD Instinct MI300X. Speed depends mainly on GPU memory bandwidth. Real-world results typically within ±20%.
tok/s = (bandwidth GB/s ÷ model GB) × efficiency
Example: AMD Instinct MI300X → 5300 ÷ 116.9 × 0.55 = ~25 tok/s
Estimated speed at IQ4_XS (116.9 GB)
~25 tok/s~15 tok/sReal-world results typically within ±20%. Speed depends on batch size, quantization kernel, and software stack.
- What's the download size of Step 3.5 Flash Base?
At IQ4_XS, the download is about 106.30 GB.
- Which GPUs can run Step 3.5 Flash Base?
No single consumer GPU has enough VRAM to run Step 3.5 Flash Base at IQ4_XS (116.9 GB). Multi-GPU or professional hardware is required.
- Which devices can run Step 3.5 Flash Base?
5 devices with unified memory can run Step 3.5 Flash Base at IQ4_XS (116.9 GB), including Mac Pro M2 Ultra (192 GB), Mac Studio M2 Ultra (192 GB), Mac Studio M4 Max (128 GB), NVIDIA DGX A100 640GB. Apple Silicon Macs use unified memory shared between CPU and GPU, making them well-suited for local LLM inference.