Step 3.5 Flash Base Midtrain — Hardware Requirements & GPU Compatibility
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Step 3.5 Flash Base Midtrain is a 197.8B-parameter open language model from StepFun in the Step 3 family. It supports a context window of up to 131,072 tokens. At Q4_K_M it needs about 130.53 GB of VRAM — see which GPUs and Macs can run it below.
172 downloads
36 likesSpecifications
- Publisher
- StepFun
- Family
- Step 3
- Parameters
- 197.8B
- Architecture
- Step3p5ForCausalLM
- Context Length
- 131,072 tokens
- Vocabulary Size
- 128,896
- Release Date
- 2026-03-02
- License
- Apache 2.0
Get Started
HuggingFace
How Much VRAM Does Step 3.5 Flash Base Midtrain Need?
Select a quantization to see compatible GPUs below.
| Quantization | Bits | VRAM | + Context | File Size | Quality |
|---|---|---|---|---|---|
| Q2_Kest. | 3.40 | 92.5 GB | — | 84.05 GB | 2-bit quantization with K-quant improvements |
| Q3_K_Mest. | 3.90 | 106.0 GB | — | 96.41 GB | 3-bit medium quantization |
| Q4_K_Mest. | 4.80 | 130.5 GB | — | 118.66 GB | 4-bit medium quantization — most popular sweet spot |
| Q5_K_Mest. | 5.70 | 155 GB | — | 140.91 GB | 5-bit medium quantization — good quality/size tradeoff |
| Q6_Kest. | 6.60 | 179.5 GB | — | 163.16 GB | 6-bit quantization, very good quality |
| Q8_0est. | 8.00 | 217.5 GB | — | 197.77 GB | 8-bit quantization, near-lossless |
| BF16est. | 16.00 | 435.1 GB | — | 395.53 GB | Brain floating point 16 — preferred for training |
est.= calculated VRAM estimate; no published GGUF file found for that quantization yet. Other rows are verified against real community uploads.
Which GPUs Can Run Step 3.5 Flash Base Midtrain?
Q4_K_M · 130.5 GBStep 3.5 Flash Base Midtrain (Q4_K_M) requires 130.5 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 170+ 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 Midtrain?
Q4_K_M · 130.5 GB6 devices with unified memory can run Step 3.5 Flash Base Midtrain, including NVIDIA DGX H100, NVIDIA DGX A100 640GB, Mac Studio (M3 Ultra, 256GB).
Runs great
— Plenty of headroom
Decent
— Enough memory, may be tightRelated Models
Frequently Asked Questions
- How much VRAM does Step 3.5 Flash Base Midtrain need?
Step 3.5 Flash Base Midtrain requires 130.5 GB of VRAM at Q4_K_M, or 435.1 GB at BF16.
VRAM = Weights + KV Cache + Overhead
Weights = 197.8B × 4.8 bits ÷ 8 = 118.7 GB
KV Cache + Overhead ≈ 11.8 GB (at 2K context + ~0.3 GB framework)
VRAM usage by quantization
Q4_K_M130.5 GB- Can NVIDIA GeForce RTX 5090 run Step 3.5 Flash Base Midtrain?
No — Step 3.5 Flash Base Midtrain requires at least 92.5 GB at Q2_K, which exceeds the NVIDIA GeForce RTX 5090's 32 GB of VRAM.
- What's the best quantization for Step 3.5 Flash Base Midtrain?
For Step 3.5 Flash Base Midtrain, Q4_K_M (130.5 GB) offers the best balance of quality and VRAM usage. Q5_K_M (155 GB) provides better quality if you have the VRAM. The smallest option is Q2_K at 92.5 GB.
VRAM requirement by quantization
Q2_K92.5 GBQ4_K_M ★130.5 GBQ5_K_M155.0 GBQ6_K179.5 GBQ8_0217.5 GBBF16435.1 GB★ Recommended — best balance of quality and VRAM usage.
- Can I run Step 3.5 Flash Base Midtrain on a Mac?
Step 3.5 Flash Base Midtrain requires at least 92.5 GB at Q2_K, 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 Midtrain locally?
Yes — Step 3.5 Flash Base Midtrain can run locally on consumer hardware. At Q4_K_M quantization it needs 130.5 GB of VRAM. Popular tools include Ollama, LM Studio, and llama.cpp.
- How fast is Step 3.5 Flash Base Midtrain?
At Q4_K_M, Step 3.5 Flash Base Midtrain can reach ~34 tok/s on AMD Instinct MI350X. Speed depends mainly on GPU memory bandwidth. Real-world results typically within ±20%.
tok/s = (bandwidth GB/s ÷ model GB) × efficiency
Example: NVIDIA B200 → 8000 ÷ 130.5 × 0.65 = ~40 tok/s
Estimated speed at Q4_K_M (130.5 GB)
~40 tok/s~40 tok/s~34 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 Midtrain?
At Q4_K_M, the download is about 118.66 GB. The full-precision BF16 version is 395.53 GB. The smallest option (Q2_K) is 84.05 GB.
- Which GPUs can run Step 3.5 Flash Base Midtrain?
No single consumer GPU has enough VRAM to run Step 3.5 Flash Base Midtrain at Q4_K_M (130.5 GB). Multi-GPU or professional hardware is required.
- Which devices can run Step 3.5 Flash Base Midtrain?
6 devices with unified memory can run Step 3.5 Flash Base Midtrain at Q4_K_M (130.5 GB), including Mac Pro M2 Ultra (192 GB), Mac Studio (M3 Ultra, 256GB), Mac Studio (M3 Ultra, 512GB), Mac Studio M2 Ultra (192 GB). Apple Silicon Macs use unified memory shared between CPU and GPU, making them well-suited for local LLM inference.