Step 3.5 Flash REAP 121B A11B — Hardware Requirements & GPU Compatibility
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Step 3.5 Flash REAP 121B A11B is a 121.0B-parameter open language model from Cerebras. It supports a context window of up to 262,144 tokens. At Q4_K_M it needs about 79.84 GB of VRAM — see which GPUs and Macs can run it below.
123 downloads
9 likesSpecifications
- Publisher
- Cerebras
- Parameters
- 121.0B
- Architecture
- Step3p5ForCausalLM
- Context Length
- 262,144 tokens
- Vocabulary Size
- 128,896
- Release Date
- 2026-02-25
- License
- Other
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HuggingFace
How Much VRAM Does Step 3.5 Flash REAP 121B A11B Need?
Select a quantization to see compatible GPUs below.
| Quantization | Bits | VRAM | + Context | File Size | Quality |
|---|---|---|---|---|---|
| Q2_Kest. | 3.40 | 56.5 GB | — | 51.41 GB | 2-bit quantization with K-quant improvements |
| Q3_K_Mest. | 3.90 | 64.9 GB | — | 58.97 GB | 3-bit medium quantization |
| Q4_K_Mest. | 4.80 | 79.8 GB | — | 72.58 GB | 4-bit medium quantization — most popular sweet spot |
| Q5_K_Mest. | 5.70 | 94.8 GB | — | 86.19 GB | 5-bit medium quantization — good quality/size tradeoff |
| Q6_Kest. | 6.60 | 109.8 GB | — | 99.80 GB | 6-bit quantization, very good quality |
| Q8_0est. | 8.00 | 133.1 GB | — | 120.97 GB | 8-bit quantization, near-lossless |
| BF16est. | 16.00 | 266.1 GB | — | 241.93 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 REAP 121B A11B?
Q4_K_M · 79.8 GBStep 3.5 Flash REAP 121B A11B (Q4_K_M) requires 79.8 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 104+ GB is recommended. No single GPU has enough memory — multi-GPU or cluster setups are needed.
Which Devices Can Run Step 3.5 Flash REAP 121B A11B?
Q4_K_M · 79.8 GB18 devices with unified memory can run Step 3.5 Flash REAP 121B A11B, including NVIDIA DGX H100, NVIDIA DGX A100 640GB, ASUS Ascent GX10.
Runs great
— Plenty of headroom
Decent
— Enough memory, may be tightFrequently Asked Questions
- How much VRAM does Step 3.5 Flash REAP 121B A11B need?
Step 3.5 Flash REAP 121B A11B requires 79.8 GB of VRAM at Q4_K_M, or 266.1 GB at BF16.
VRAM = Weights + KV Cache + Overhead
Weights = 121.0B × 4.8 bits ÷ 8 = 72.6 GB
KV Cache + Overhead ≈ 7.2 GB (at 2K context + ~0.3 GB framework)
VRAM usage by quantization
Q4_K_M79.8 GB- Can NVIDIA GeForce RTX 5090 run Step 3.5 Flash REAP 121B A11B?
No — Step 3.5 Flash REAP 121B A11B requires at least 56.5 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 REAP 121B A11B?
For Step 3.5 Flash REAP 121B A11B, Q4_K_M (79.8 GB) offers the best balance of quality and VRAM usage. Q5_K_M (94.8 GB) provides better quality if you have the VRAM. The smallest option is Q2_K at 56.5 GB.
VRAM requirement by quantization
Q2_K56.5 GBQ4_K_M ★79.8 GBQ5_K_M94.8 GBQ6_K109.8 GBQ8_0133.1 GBBF16266.1 GB★ Recommended — best balance of quality and VRAM usage.
- Can I run Step 3.5 Flash REAP 121B A11B on a Mac?
Step 3.5 Flash REAP 121B A11B requires at least 56.5 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 REAP 121B A11B locally?
Yes — Step 3.5 Flash REAP 121B A11B can run locally on consumer hardware. At Q4_K_M quantization it needs 79.8 GB of VRAM. Popular tools include Ollama, LM Studio, and llama.cpp.
- How fast is Step 3.5 Flash REAP 121B A11B?
At Q4_K_M, Step 3.5 Flash REAP 121B A11B can reach ~55 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 ÷ 79.8 × 0.65 = ~65 tok/s
Estimated speed at Q4_K_M (79.8 GB)
~65 tok/s~65 tok/s~55 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 REAP 121B A11B?
At Q4_K_M, the download is about 72.58 GB. The full-precision BF16 version is 241.93 GB. The smallest option (Q2_K) is 51.41 GB.
- Which GPUs can run Step 3.5 Flash REAP 121B A11B?
No single consumer GPU has enough VRAM to run Step 3.5 Flash REAP 121B A11B at Q4_K_M (79.8 GB). Multi-GPU or professional hardware is required.
- Which devices can run Step 3.5 Flash REAP 121B A11B?
19 devices with unified memory can run Step 3.5 Flash REAP 121B A11B at Q4_K_M (79.8 GB), including ASUS Ascent GX10, Asus ROG Flow Z13 (2025, Ryzen AI Max+ 395, 128 GB), Beelink GTR9 Pro (Ryzen AI Max+ 395, 128 GB), Framework Desktop (Ryzen AI Max+ 395, 128 GB). Apple Silicon Macs use unified memory shared between CPU and GPU, making them well-suited for local LLM inference.