How to use from the
Use from the
MLX library
# Make sure mlx-lm is installed
# pip install --upgrade mlx-lm

# Generate text with mlx-lm
from mlx_lm import load, generate

model, tokenizer = load("majentik/Nemotron-3-Nano-4B-RotorQuant-MLX-8bit")

prompt = "Write a story about Einstein"
messages = [{"role": "user", "content": prompt}]
prompt = tokenizer.apply_chat_template(
    messages, add_generation_prompt=True
)

text = generate(model, tokenizer, prompt=prompt, verbose=True)

KV-cache quantization without any fork (recommended, 2026): upstream llama.cpp/Ollama now cover this natively — use -ctk q8_0 -ctv q8_0 (half KV memory, negligible quality loss: perplexity +0.002–0.05) or -ctk q4_0 -ctv q4_0 (quarter memory, ≈7.6% perplexity increase). In Ollama: OLLAMA_KV_CACHE_TYPE=q8_0 with OLLAMA_FLASH_ATTENTION=1. Keep K and V types symmetric to stay on the fast fused Flash-Attention path. Since April 2026, mainline llama.cpp also applies Hadamard rotation to KV activations (PR #21038), which greatly improves low-bit KV quality (opt-out: LLAMA_ATTN_ROT_DISABLE=1).

The RotorQuant/TurboQuant fork flow below is experimental/legacy: the TurboQuant llama.cpp PR was closed without merging (June 2026) and the fork is unmaintained relative to mainline. It is NOT required to use this model.

Nemotron-3-Nano-4B - RotorQuant MLX 8-bit

8-bit weight-quantized MLX version of nvidia/NVIDIA-Nemotron-3-Nano-4B-BF16 with the legacy RotorQuant KV-cache fork (superseded by upstream llama.cpp KV options). Optimized for Apple Silicon inference via the MLX framework. The dense hybrid Mamba-2 + Attention architecture supports up to 262K context length.

Approximate model size: ~4 GB

Model Specifications

Property Value
Base Model nvidia/NVIDIA-Nemotron-3-Nano-4B-BF16
Parameters 4 billion (dense)
Architecture Hybrid Mamba-2 + Attention (dense)
Context Length 262,144 tokens (262K)
License NVIDIA Open Model License (commercial use OK)
Weight Quantization 8-bit (~4 GB)
KV-Cache Quantization RotorQuant
Framework MLX (Apple Silicon)

Quickstart

from mlx_lm import load, generate
from rotorquant import IsoQuantCache

model, tokenizer = load("majentik/Nemotron-3-Nano-4B-RotorQuant-MLX-8bit")

prompt = "Explain the theory of relativity."
response = generate(model, tokenizer, prompt=prompt, max_tokens=512)
print(response)

About the RotorQuant / TurboQuant labels

RotorQuant and TurboQuant are this project's release labels, not distinct quantization algorithms — for any given tier, both brand repos carry byte-identical weights produced with the standard MLX / llama.cpp quantizers. No brand-specific speedup is claimed or measured. The KV-cache fork these labels originally referred to is legacy; for KV-cache memory savings use the upstream options described above (-ctk/-ctv q8_0, OLLAMA_KV_CACHE_TYPE).

KV-Cache Quantization Comparison

Method Prefill Speed Decode Speed Memory Savings Reference
TurboQuant 1x (baseline) 1x (baseline) High arXiv: 2504.19874

Memory Estimates (Nemotron-3-Nano-4B)

Precision Approximate Size MLX Variant
BF16 (original) ~8 GB --
8-bit quantized ~4 GB This model
4-bit quantized ~2.3 GB RotorQuant-MLX-4bit
2-bit quantized ~1.2 GB RotorQuant-MLX-2bit

Hardware Requirements

This model requires approximately 4 GB of unified memory. Recommended hardware:

  • Apple M1 (8 GB+)
  • Apple M2 (8 GB+)
  • Apple M3 (8 GB+)
  • Apple M4 (8 GB+)
  • Any Apple Silicon Mac with 8 GB+ unified memory

See Also

Quant trade-off (MLX lane)

Bits Approx size Use case Recommendation
2-bit ~1.0 GB Aggressive quantization Very low-RAM Macs
3-bit ~1.4 GB Lossy but small Low-RAM Macs
4-bit ~1.7 GB Balanced default Recommended for most Macs
5-bit ~2.0 GB Higher fidelity Quality-sensitive
6-bit ~2.4 GB Approaching FP16 quality High-fidelity
8-bit ~3.0 GB Near-lossless reference Fidelity-critical work

(Current variant — 8bit — is bolded.)

Variants in this family

(Showing 13 sibling variants under majentik/nemotron3-nano-4b-*. The current variant — RotorQuant-MLX-8bit — is bolded.)

Variant Runtime Approx size Use case
RotorQuant-MLX-8bit mlx-lm ~4.7 GB Apple Silicon reference
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